NETGEAR Network Router XM128 ISDN User Manual

Reference Guide for the  
Model XM128 ISDN  
Digital Modem  
NETGEAR, Inc.  
A Bay Networks Company  
48105 Warm Springs Blvd.  
Fremont, CA 94539  
USA  
M-XM128NA-1  
November 1997  
 
Bestätigung des Herstellers/Importeurs  
Es wird hiermit bestätigt, daß das Model NETGEAR Model XM 128 ISDN Digital Modem gemäß der im  
BMPT-AmtsblVfg 243/1991 und Vfg 46/1992 aufgeführten Bestimmungen entstört ist. Das vorschriftsmäßige Betreiben  
einiger Geräte (z.B. Testsender) kann jedoch gewissen Beschränkungen unterliegen. Lesen Sie dazu bitte die  
Anmerkungen in der Betriebsanleitung.  
Das Bundesamt für Zulassungen in der Telekommunikation wurde davon unterrichtet, daß dieses Gerät auf den Markt  
gebracht wurde und es ist berechtigt, die Serie auf die Erfüllung der Vorschriften hin zu überprüfen.  
Certificate of the Manufacturer/Importer  
It is hereby certified that the NETGEAR Model XM128 Digital Modem has been suppressed in accordance with the  
conditions set out in the BMPT-AmtsblVfg 243/1991 and Vfg 46/1992. The operation of some equipment (for example,  
test transmitters) in accordance with the regulations may, however, be subject to certain restrictions. Please refer to the  
notes in the operating instructions.  
Federal Office for Telecommunications Approvals has been notified of the placing of this equipment on the market and  
has been granted the right to test the series for compliance with the regulations.  
VCCI-2 Statement  
This equipment is in the second Class category (information equipment to be used in a residential area or an adjacent  
area thereto) and conforms to the standards set by the Voluntary Control Council for Interference by Data Processing  
Equipment and Electronic Office Machines aimed at preventing radio interference in such residential areas.  
When used near a radio or TV receiver, it may become the cause of radio interference.  
Read instructions for correct handling.  
Customer Support  
For assistance with installing and configuring your NETGEAR system or with post-installation questions or problems,  
contact your point of purchase representative.  
To contact customer support or to purchase additional copies of this document and publications for other NETGEAR  
products, you can contact NETGEAR at the following numbers:  
Phone:  
U.S./Canada:1-800-211-2069  
Japan: 0120-66-5402  
Europe: (44) 171-571-5120  
Australia:1-800-142-046  
Fax:  
U.S./Canada: 510-498-2609  
iii  
 
 
World Wide Web  
NETGEAR maintains a World Wide Web Home Page that you can access at the universal resource locator (URL)  
http://NETGEAR.baynetworks.com. A direct connection to the Internet and a Web browser such as Internet Explorer  
or Netscape are required.  
Bulletin Board Service  
NETGEAR maintains a bulletin board that you can access to obtain information about the latest version of the software.  
In the United States, phone 407-531-4574.  
iv  
 
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Contents  
Preface  
Conventions ...................................................................................................................xviii  
Use of Enter, Type, and Press .................................................................................xviii  
Introduction  
Interface Options ......................................................................................................1-3  
Chapter 2  
Installation  
Package Contents ..........................................................................................................2-1  
Verifying Hardware Installation .......................................................................................2-3  
Chapter 3  
Setup for Windows 95 and Windows NT 4.0  
Selecting the Appropriate Windows 95 Driver (INF file) .................................................3-1  
Contents  
v
 
Configuration  
Communication Speed Setup ..................................................................................4-4  
SPID Setup for North America ...........................................................................4-6  
Async to Sync PPP  
Multilink PPP ............................................................................................................5-3  
Dialing Pre-stored Phone Numbers .........................................................................5-4  
Dialing Out Using ISDN Mode Optional Speech Bearer Service .............................6-2  
Dialing Out for Analog Adapter Port 1 ......................................................................6-2  
Dialing Out for Analog Adapter Port 2 ......................................................................6-2  
Manually Switching Communication Modes .............................................................6-2  
Placing the Call ........................................................................................................6-3  
vi  
Contents  
 
Configuring the V.120 Mode ......................................................................6-12  
Making an X.75 Call ........................................................................................6-17  
Dialing Prestored Phone Numbers ............................................................6-18  
Invoking V.42bis Data Compression ..........................................................6-18  
Bundle Connection with V.42bis Data Compression .................................6-19  
Contents  
vii  
 
Advanced ISDN  
Point-to-Point Configuration .............................................................................7-11  
Placing a Call for DSS1 ..........................................................................................7-11  
Analog Call Handling  
Chapter 9  
Modem Upgrade  
Upgrading with Flash EPROM ........................................................................................9-1  
Upgrade Instructions ................................................................................................9-2  
Kernel Mode .............................................................................................................9-2  
viii  
Contents  
 
Troubleshooting  
Using The Embedded Protocol Analyzer ...............................................................10-4  
Capturing the Protocol Data ............................................................................10-5  
...............................................................................................................................10-8  
Appendix A  
Security Functions  
Level 1 Security ....................................................................................................... B-2  
Level 3 Security ....................................................................................................... B-3  
AT Command Set Reference  
Simplex Mode ......................................................................................................... C-1  
AT Command Descriptions ............................................................................................ C-2  
Description of ATI3 Output ...................................................................................... C-7  
Contents  
ix  
 
Status Registers and Result Codes  
S-Register Descriptions .......................................................................................... D-4  
Result Code Chart Symbol Reference .................................................................. D-21  
Connector Pin Assignments  
Serial Port Interface  
ISDN Reference  
Order Form for AT&T 5ESS Switch (NI-1 ISDN) ............................................................G-6  
Order Form for DMS-100 Switch (NI-1 or Custom ISDN) ..............................................G-7  
Order Form for EWSD (NI-1 ISDN) ...............................................................................G-8  
Index  
x
Contents  
 
Figures  
Figure 1-2. Front panel of the Model XM128 modem (with U interface) .....................1-4  
Figure 2-1. Model XM128 modem connections ..........................................................2-2  
Figure E-1. RJ-45 plug and RJ-45 connector ............................................................ E-1  
Figure E-2. RJ-11 plug and RJ-11 connector ............................................................ E-3  
Figures  
xi  
 
xii  
Figures  
 
Tables  
Table 4-2.  
Table 4-4.  
Supported AT command types .................................................................4-3  
Switches supported by the Model XM128 modem ..................................4-5  
Table 6-2.  
Table 6-3.  
Table 6-4.  
Table 6-5.  
Table 6-6.  
Call placing commands ............................................................................6-3  
Commands for assigning ISDN numbers .................................................6-6  
Best-effort call answering bit commands .................................................6-8  
ISDN protocol specifications ....................................................................6-9  
V.110 configuration commands ..............................................................6-10  
Tables  
xiii  
 
Table 7-1.  
S-register values and functions ................................................................7-2  
Table 9-1.  
Definitions for the d modifier ....................................................................9-1  
Table 10-4. Control key functions .............................................................................10-7  
Table D-4.  
Table D-5.  
Table D-6.  
Table D-7.  
Table D-8.  
Extended S-registers ATSn=x ................................................................. D-5  
ATXn command setting options ............................................................ D-19  
Result code chart .................................................................................. D-21  
Result code field descriptions ............................................................... D-22  
Connect strings ..................................................................................... D-23  
xiv  
Tables  
 
Table E-2.  
Table F-1.  
Table F-2.  
RJ-45 plug and RJ-45 connector pin assignments for the U interface .... E-2  
Asynchronous flow control cable connection ...........................................F-2  
Table G-1.  
Table G-2.  
Table G-3.  
ISDN line configuration ...........................................................................G-6  
ISDN line configuration ...........................................................................G-7  
ISDN line configuration ...........................................................................G-8  
Tables  
xv  
 
xvi  
Tables  
 
Preface  
Congratulations on your purchase of the NETGEARModel XM128 ISDN Digital Modem.  
The NETGEAR Model XM128 modem provides connection for one or more PCs to the Internet  
or to the office over ISDN (Integrated Services Digital Network) lines. The modem operates  
at a speed of up to 460 kilobits per second (Kbps) data rate, or 115 Kbps data rate without  
compression, and can download video clips, music, or high-resolution color graphics from the  
World Wide Web or other online services many times faster than an analog modem. The Model  
XM128 modem supports concurrent data and voice communications, reducing cost and  
administration of multiple phone lines.  
Purpose  
This guide provides instructions for the installation and use of the Model XM128 modem. This  
guide also provides instructions for the installation and use of FirstGear, a configuration software  
application for installing, configuring, and monitoring the Model XM128 modem.  
Preface  
xvii  
 
   
Reference Guide for the Model XM128 ISDN Digital Modem  
Conventions  
This section describes the conventions used in this guide.  
Special Message Formats  
This guide uses the following formats to highlight special messages.  
Note: This format is used to highlight information of importance or special interest.  
Caution: This format is used to highlight information that will help you prevent  
equipment failure or loss of data.  
Warning: This format is used to highlight material involving possibility of injury or  
equipment damage.  
Use of Enter, Type, and Press  
This guide uses “enter,” “type,” and “press” to describe the following actions:  
When you read “enter,” type the text and press the Enter key.  
When you read “type,” type the text, but do not press the Enter key.  
When you read “press,” press only the alphanumeric or named key.  
When you read “click,” click the left mouse button.  
xviii  
Preface  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
Other Conventions  
This guide uses the following additional conventions:  
italics  
Book titles and UNIX file, command, and directory names.  
courier font  
Initial Caps  
[Enter]  
Screen text, user-typed command-line entries.  
Menu titles and window and button names.  
Named keys in text are shown enclosed in square brackets. The notation  
[Enter] is used for the Enter key and the Return key.  
[Ctrl]+C  
Two or more keys that must be pressed simultaneously are shown in text  
linked with a plus (+) sign.  
ALL CAPS  
DOS file and directory names.  
Related Publication  
Refer to Getting Started Using FirstGear for the Model XM128 ISDN Digital Modem for a quick  
installation guide. Refer to Table 1 to identify the contents of both manuals. The subject column in  
this table identifies the order of basic procedures you must complete to install your Model XM128  
modem.  
Table 1.  
Subject  
Manual contents  
Getting Started Using FirstGear  
Reference Guide for the Model  
XM128 ISDN Digital Modem  
for the Model XM128 ISDN Digital  
Modem  
Installing modem hardware  
Configuring the modem  
Chapter 3  
Chapter 2  
Chapter 3  
(If you are using Windows® 95  
or Windows NT®)  
Chapter 4  
(If you are using a terminal  
program.)  
Installing the Windows 95 and  
Windows NT Driver  
Chapter 3  
No information given.  
Installing FirstGear  
Chapter 3  
Chapter 3  
No information given.  
Assigning ISDN numbers  
Chapter 4 and Chapter 5  
(For using AT commands when  
assigning ISDN numbers.)  
Preface  
xix  
 
         
Reference Guide for the Model XM128 ISDN Digital Modem  
Table 1.  
Subject  
Manual contents (continued)  
Getting Started Using FirstGear  
Reference Guide for the Model  
XM128 ISDN Digital Modem  
for the Model XM128 ISDN Digital  
Modem  
Assigning multiple subscriber  
numbers  
Chapter 3  
Chapter 5  
(For using AT commands when  
assigning multiple subscriber  
numbers.)  
Assigning protocols  
Chapter 3  
Chapter 4 and Chapter 5  
(For using AT commands when  
assigning protocols.)  
Configuring Windows 95 Dial-Up Chapter 3  
Networking  
See: Getting Started Using  
FirstGear  
Table 2 lists the manuals that are available for various localized products.  
Table 2.  
Manuals  
Product Model/  
Version  
Reference  
Manual  
FirstGear  
Manual  
Language  
Interface  
English  
Model XM128S  
International  
S/T  
M-XM128NA-0  
M-XM128NA-0  
M-XM128JP-0  
M-XM128NA-0  
M-XM128KO-0  
M1-XM128S-0  
M1-XM128U-0  
M1-XM128JP-0  
M1-XM128S-0  
M1-XM128KO-0  
English  
Model XM128AU  
North America  
U
Japanese  
German  
Korean  
Model XM128D  
Japanese  
DSU  
S/T  
U
Model XM128GE  
German  
Model XM128KO  
Korean  
xx  
Preface  
 
   
Chapter 1  
Introduction  
Congratulations on your purchase of the NETGEAR Model XM128 ISDN Digital Modem. The  
Model XM128 modem sets a new price and performance standard for the rapidly growing Internet  
and telecommuting applications.  
When used with off-the-shelf Internet or remote access client software, the Model XM128 modem  
enables mobile or home users to easily connect to the Internet or branch offices over Integrated  
Services Digital Network (ISDN) lines. The same device also allows a user to connect to the  
analog world via a modem, fax machine, or telephone connected directly to the Model XM128  
modem.  
To take advantage of constant new developments, the Model XM128 modem employs flash  
EPROMs, which allow for convenient uploading of newly available firmware that preserves your  
hardware investment.  
The Model XM128 modem supports both D and B channel protocols. For the D channel,  
it supports DSS1, 1TR6, DMS-100, AT&T Custom, and NI-1. For the B channel, it supports  
X.75 SLIP, V.120, V.110, PPP Async-to-sync Conversion and Bundle (128 Kbps).  
With its Hi/fn LZS or V.42bis compression on the B channel using either X.75 or V.120, the Model  
XM128 modem can effectively communicate at speeds up to 460 kilobits per second (Kbps) over  
ISDN lines.  
Features  
The Model XM128 modem supports a variety of compression schemes including V.42bis and  
Hi/fn LZS Compression (STAC) and communicates effectively at speeds up to 460 kilobits per  
second (Kbps) over ISDN lines.  
Introduction  
1-1  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
The Model XM128 modem has two analog ports to connect analog devices such as fax machines,  
modems, and telephones. Two different devices can communicate over the two B channels to  
different locations simultaneously, enabling you to send a fax and make a voice call at the same  
time. The analog ports recognize standard dual-tone multifrequency (DTMF) tones as well as  
pulse dialing.  
The Model XM128 modem has the following features:  
Plug-and-Play support for a windows 95® environment  
Full compatibility with both ISDN and remote public-switched telephone network (PSTN) by  
way of ISDN  
Multiple signaling protocol compatibility with DSS1, 1TR6, NI-1, AT&T 5ESS, and Northern  
Telecom DMS 100 network switches  
X.75, V.110, V.120, and Point-to-Point Protocol (PPP) Async-to-Sync Conversion B Channel  
Protocol support  
B channel speeds of 56 Kbps (in-band signaling) and 64 Kbps (out-of-band signaling)  
MLP and Multipoint PPP (RFC1717)  
Hi/fn LZS compression (STAC)  
V.42bis data compression using the X.75, V.120, and bundle protocols  
NETGEAR ISDN AT modem commands  
Automatic ISDN and analog call detection  
Two analog telephone jacks (analog adapters)  
Push-button switch for quick dial and teardown  
Easy-to-use configuration software  
Flash EPROM memory for easy firmware upgrades  
1-2  
Introduction  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Interface Options  
Several interfaces are available. Table 1-1 lists the interface options for the Model XM128 modem  
as applicable for each region.  
Table 1-1.  
Interface options  
XM128NA XM128GE  
XM128UK  
XM128AU  
XM128JP  
Unit  
XM128U  
XM128S  
Germany  
XM128S  
UK  
XM128S  
Australia  
S/T  
XM128D  
Japan  
Region  
North America  
Interface U (internal NT-1) S/T  
Auto SPID Switch  
S/T  
Internal DSU  
For the North American ISDN, NETGEAR provides an optional 2B1Q U interface to allow direct  
connection to the network without the use of an external NT-1 device.  
Front Panel  
For easier management and control of the Model XM128 modem, familiarize yourself with the  
components on the front panel, as illustrated in Figure 1-1 and Figure 1-2. Use the key at the  
bottom of each illustration to identify the panel components.  
1
2
3
4
INTERFACE  
128Kpbs  
MODELXM128  
S
ISDN Digital Modem  
PWR  
D
B1  
B2  
ISDN  
AA  
CP  
DTR DSR RTS CTS  
TD  
RD  
1
2
COM  
7848MEA  
Key:  
1 = PWR (power) LED  
2 = ISDN LEDs  
3 = RS-232 COM LEDs  
4 = PHONE 1 and PHONE 2 LEDs  
Figure 1-1.  
Front panel of the Model XM128 modem (with S/T interface)  
Introduction  
1-3  
 
               
Reference Guide for the Model XM128 ISDN Digital Modem  
1
2
3
4
INTERFACE  
128Kpbs  
MODELXM128  
U
ISDN Digital Modem  
PWR  
D
B1  
B2  
ISDN  
AA  
CP  
DTR DSR RTS CTS  
TD  
RD  
1
2
COM  
7847MEA  
Key:  
1 = PWR (power) LED  
2 = ISDN LEDs  
3 = RS-232 COM LEDs  
4 = PHONE 1 and PHONE 2 LEDs  
Figure 1-2.  
Front panel of the Model XM128 modem (with U interface)  
LEDs on the front panel of the Model XM128 modem allow you to monitor and diagnose the  
device. Table 1-2 describes each LED.  
Table 1-2.  
Label  
LED descriptions  
Color  
Activity  
Description  
PWR  
(Power)  
Yellow  
Green  
On  
Power is supplied to the modem.  
ISDN LEDs:  
D
On  
The ISDN link on the D channel is active.  
Blinking  
On  
The modem is attempting to make a connection to the switch.  
A connection is established to the B1 channel.  
A connection is established to the B2 channel.  
The Model XM128 modem is in the automatic answering mode.  
An incoming call is ringing.  
B1  
B2  
AA  
CP  
On  
On  
Blinking  
On  
Compression is active on either of the B channels.  
1-4  
Introduction  
 
           
Reference Guide for the Model XM128 ISDN Digital Modem  
LED descriptions (continued)  
Table 1-2.  
Label  
Color  
Activity  
Description  
COM LEDs:  
DTR  
Green  
On  
The data terminal or computer connected to the COM port on  
the Model XM128 modem is ready to communicate.  
DSR  
RTS  
On  
The Model XM128 modem is ready to communicate with the  
connected data terminal or computer.  
On  
The data terminal or computer connected to the COM port on  
the Model XM128 modem is ready to transmit data.  
CTS  
On  
The Model XM128 modem is ready to accept data from the  
connected data terminal or computer.  
TD  
Blinking  
On  
The data terminal or computer connected to the Model XM128  
modem is transmitting data to the modem.  
RD  
The data terminal or computer connected to the Model XM128  
modem is receiving data from the DTE port of the modem.  
PHONE 1  
PHONE 2  
On  
The handset of the telephone connected to the port is not  
properly placed in the receiver cradle.  
On  
The handset of the telephone connected to the port is not  
properly placed in the receiver cradle.  
Introduction  
1-5  
 
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Rear Panel  
As illustrated in Figure 1-3 and Figure 1-4, the rear panel contains a power switch, a power  
receptacle, and ports to connect a computer, ISDN line, and two analog devices (phone, fax, or  
modem).  
4
5
1
2
3
ON/OFF  
ISDN-S  
PHONE 1PHONE 2  
POWER  
RS-232  
7861MEA  
key:  
1 = ON/OFF switch  
2 = Receptacle for power adapter  
3 = RS-232 COM port for connecting to a computer  
4 = ISDN port for connecting to an ISDN line NT-1  
5 = PHONE 1 and PHONE 2 ports for connecting analog devices (telephone, fax, or modem)  
Figure 1-3.  
Rear panel of the Model XM128 modem (with S interface)  
4
5
1
2
3
ON/OFF  
ISDN-U  
PHONE 1PHONE 2  
POWER  
RS-232  
7862MEA  
Key:  
1 = ON/OFF switch  
2 = Receptacle for power adapter  
3 = RS-232 COM port for connecting to a computer  
4 = ISDN port for connecting to an ISDN line  
5 = PHONE 1 and PHONE 2 ports for connecting analog devices (telephone, fax, or modem)  
Figure 1-4.  
Rear panel of the Model XM128 modem (with U interface)  
1-6  
Introduction  
 
             
Reference Guide for the Model XM128 ISDN Digital Modem  
Table 1-3 describes the components on the rear panel of the Model XM128 modem.  
Table 1-3.  
Label  
Rear panel components  
Description  
ON/OFF  
POWER  
RS-232  
This switch turns power on or off.  
This is the power receptacle for the power adapter.  
This RS-232 COM port is for connecting the Model XM128 modem to the serial port  
of a computer or data terminal.  
ISDN  
This port is for connecting the RJ-45 connector of an ISDN line.  
PHONE 1  
This port is for connecting the RJ-11 connector of an analog device (telephone, fax,  
or analog modem).  
PHONE 2  
This port is for connecting the RJ-11 connector of an analog device (telephone, fax,  
or analog modem).  
Introduction  
1-7  
 
             
 
Chapter 2  
Installation  
This chapter information about installing and using the Model XM128 ISDN Digital Modem.  
Package Contents  
Your package should contain the following items:  
Model XM128 ISDN Digital Modem  
Power adapter  
RJ-45 ISDN telephone cable  
Shielded RS-232 25-pin to 25-pin cable  
25-pin to 9-pin adapter  
This manual  
Getting Started Using FirstGear  
CD ROM with bundled software  
3.5-inch driver and utility diskettes  
Warranty Registration Card  
Call your reseller or customer support in your area if there are any wrong, missing, or damaged  
parts. Refer to page iii for the location of customer support in your area.  
Keep the carton, including the original packing materials. Use them to repack the modem if you  
need to return it for repair.  
Installation  
2-1  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
To qualify for product updates and product warranty registrations, fill in the Warranty and Owner  
Registration Card within 30 days of purchase and return it to NETGEAR, Inc.  
Installing the Modem  
Before connecting any of the devices to your modem, make sure the power is turned off on your  
computer and your Model XM128 modem. If connecting to the model with the S/T interface, you  
must use an NT-1 device, which converts the S/T interface to a U interface. If connecting to the  
Model XM128 modem with the U interface, you can connect directly to your ISDN line. Refer to  
Figure 2-1 and then the detailed steps that follow for making those connections.  
1
6
2
6
4
5
3
7860MEA  
Key:  
1 = Model XM128 modem  
2 = AC power adapter  
3 = Station (PC, Macintosh, or UNIX workstation)  
4 = Shielded RS-232 25-pin straight cable  
5 = ISDN wall connection (connected with ISDN cable provided in package)  
6 = Analog device (telephone or fax)  
Figure 2-1.  
Model XM128 modem connections  
2-2  
Installation  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
To install your Model XM128 modem, follow these steps:  
1. Connect the male end of the 25-pin cable to the RS-232 COM port of the Model XM128  
modem.  
2. Connect the other end of the 25-pin cable (female end) to the serial (COM) port on your  
computer.  
Note: If your computer has a 9-pin serial connector, use a 25-pin to 9-pin converter  
(25-pin male to 9-pin female). If you have a Macintosh, a special cable is needed for the  
connection.  
3. Using the ISDN cable that is included, connect the RJ-45 connector on one end of the  
cable to the ISDN port on the back of the Model XM128 modem.  
4. For European models, connect the other end of the RJ-45 ISDN cable to your NT-1  
terminal or S/T interface. Using the proper cable supplied with your NT-1, connect your  
NT-1 or U interface to the wall jack installed by your phone company.  
5. For North American models, connect the other end of the RJ-45 ISDN cable to the wall  
jack installed by your phone company.  
6. Using the proper cable, insert the round end of the power adapter in the POWER  
connector on the rear panel.  
7. Plug the power supply unit into an AC wall outlet.  
8. Turn the power on to your Model XM128 modem.  
9. Turn the power on to your computer.  
Verifying Hardware Installation  
When the installation is complete and power applied to the modem, a self-test sequence begins.  
The B1, B2, and AA LED lights blink on and then off again. After this cycle is complete, the PWR  
(power) LED remains on.  
If the test routine fails, the D LED blinks. Refer to Chapter 10, “Troubleshooting,” for more  
information about the self-test and the error codes.  
Installation  
2-3  
 
     
 
Chapter 3  
Setup for Windows 95 and Windows NT 4.0  
This chapter contains step-by-step procedures both for installing the Windows NT and  
Windows 95 drivers and for configuring Dial-Up Networking for the Model XM128 modem.  
Selecting the Appropriate Windows 95 Driver (INF file)  
If your computer supports the Plug-and-Play feature, be sure your Model XM128 modem is  
powered on before starting your computer. If you are using a non-Plug-and-Play protocol, follow  
the steps to complete installation:  
1. Open the Control Panel by double-clicking the Control Panel icon in your My Computer  
folder.  
2. Double-click on Modems.  
3. Click on Add.  
The Install New Modem screen appears.  
4. Select Don't detect my modem; I will select from a list.  
5. Click on Next.  
6. Click on Have Disk.  
7. Insert the NETGEAR Windows 95 driver disk into your floppy drive and click on OK.  
8. If you have downloaded an updated INF file from NETGEAR’s Web site or BBS, use  
Browse to find the location of the updated INF file, click on Open, then click on OK.  
Setup for Windows 95 and Windows NT 4.0  
3-1  
 
   
Reference Guide for the Model XM128 ISDN Digital Modem  
9. Select the Model XM128 modem driver with the protocol that your host is using.  
Generally, the following examples work. However, we recommend that you verify  
the protocol your Internet service provider (ISP) uses.  
If you are connecting to an Internet service provider (ISP), select:  
NETGEAR XM128, PPP 64K  
If the ISP has not upgraded to an ASCEND compatible server, select:  
NETGEAR XM128 V.120 64K  
If you are calling another location such as a BBS system, select:  
NETGEAR XM128 V.120 64K  
If you dial up to CompuServe, select:  
NETGEAR XM128 V.120 64K  
If you are calling the Microsoft Network (MSN) ISDN line, select:  
NETGEAR XM128, PPP 64K  
10. After you have completed the selections above, click on Next.  
11. Select the COM port your modem is connected to and click on Next.  
A final dialog box will appear.  
12. Click on Finish.  
The Modems Properties screen is displayed.  
13. Click on Close.  
This step completes the installation of your Model XM128 modem driver. You may now  
use programs such as Dial-Up Networking with your modem.  
3-2  
Setup for Windows 95 and Windows NT 4.0  
 
Chapter 4  
Configuration  
This chapter describes the procedures for configuring your Model XM128 modem and your ISDN  
line.  
Configuring Your ISDN Line and Network  
The setup procedure for the Model XM128 modem needs to be done only once. The settings are  
stored in the nonvolatile random access memory (NVRAM) of the modem. Turning power on and  
off will not erase the information. The only time that you need to reconfigure your line is when you  
perform a hardware reset on your modem when you change options on your ISDN line.  
NETGEAR provides a simple Windows 95 or NT 4.0 utility to help you set up the Model XM128  
modem. Refer to Getting Started Using FirstGear for the XM128 ISDN Digital Modem for  
complete instructions. This chapter explains how to set up your switch using the Windows/  
Windows 95 utility that comes with the modem.  
If your Model XM128 modem is not going to be set up by a computer running Windows, use  
a terminal program that allows you to send AT commands to the modem and receive responses  
from it.  
Configuring Your Modem Using a Terminal Program  
If you are not running Windows 95 or Windows NT, configure your Model XM128 modem with  
a terminal program that allows you to send and receive AT commands and responses from the  
modem.  
NETGEAR recommends that you have your Model XM128 modem ready to use before the  
telephone company installs your ISDN line. If the modem is ready, you can enter the SPID and  
confirm that the ISDN network is responding properly before the telephone installer leaves.  
Configuration  
4-1  
 
         
Reference Guide for the Model XM128 ISDN Digital Modem  
The setup procedure for the Model XM128 modem needs to be done only once because the  
settings are stored in the nonvolatile RAM of the modem and turning the power off does not erase  
the information. The only time you have to reconfigure your line is when you perform a hardware  
reset or when you change options on your ISDN line.  
Note: If you perform a hardware reset and have to reenter the SPID number(s) and switch  
type again, it is easier if you write down or store all the relevant information so it can be  
easily retrieved.  
Table 4-1 shows a list of example terminal programs for different operating platforms. For  
instructions on how to use a terminal program, refer to the instructions that came with the program.  
Table 4-1.  
Terminal programs  
Operating system  
Program  
Windows 95  
Windows 3.x  
Hyper Terminal  
Terminal  
Procomm Plus for Windows  
Qmodem for Windows  
UNIX  
DOS  
Minicomm  
PC Plus  
Qmodem  
Macintosh  
Z-Term  
Communicate Lite  
Understanding AT Commands  
AT commands configure and control the Model XM128 modem through a terminal program.  
Command statements are usually sent to the modem from the computer keyboard.  
Command statements must be written in a specific form in order for the Model XM128 modem to  
recognize them. A command statement begins with the letters AT or at. It is then followed by one  
or more commands and the Enter key.  
AT commands can be issued only when the Model XM128 modem is in command or offline mode.  
After the Model XM128 modem has established a connection with the remote device, it goes into  
online mode, and the characters sent from your computer (through the modem) are transmitted  
to the remote device.  
4-2  
Configuration  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
In order to issue an AT command statement, you first need to run your communications software  
and configure it to the port connected to the Model XM128 modem. Refer to your communications  
software manual for more information.  
Table 4-2 lists the supported AT command types.  
Table 4-2.  
Supported AT command types  
Type of AT command  
Example  
Basic AT (Hayes compatible)  
Basic AT$ (online Help)  
Extended AT&  
ATA  
AT$  
AT&F  
AT*I1  
ATS0=1  
Extended AT* command  
S-Register command  
S-Register bitmapped command ATS13.1=1  
(set S-Register bit 1 equal to 1)  
Register inquiry command  
SATS0? or ATS13.1?  
You can also browse the list by using the command AT$.  
Quick Tips for Issuing AT Commands  
The following is a list of quick tips when issuing AT commands:  
The [Enter] key must be pressed to execute a command.  
Multiple AT commands can be combined into one line (for example, AT&O2 and ATB02 are  
combined as follows: AT&O2B02).  
The Model XM128 modem processes commands from left to right. The AT command that  
appears to the right might overwrite the command to the left (for example, ATB13B14 results  
in ATB14 because both B13 and B14 cannot coexist).  
If you see duplicated characters for each one you type, your Model XM128 modem and  
software both have their echo feature turned on (the modem defaults to enable command  
echo). To eliminate the double characters, turn off software command echo.  
Use A/ to repeat the last command. No AT prefix is needed for this command.The Model  
XM128 modem supports either verbose result code (OK, for example) or numerical result  
code (0, for example). You can use the ATVn command to set it one way or the other.  
Configuration  
4-3  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
Table 4-3 lists the commands for viewing both the numerical and verbose result codes.  
Table 4-3.  
Command  
Result codes commands  
Description  
ATV0  
ATV1  
Select numerical result code  
Select verbose result code  
Using AT Commands to Verify Modem Response  
Use AT commands to make sure the Model XM128 modem responds, and follow these steps:  
1. Type the command AT and press [Enter].  
You should receive the following response:  
OK  
2. Type the command ATI and press [Enter].  
You should receive the following response:  
1291  
3. Type the command ATI1 and press [Enter].  
You should receive the following response:  
NETGEAR XM128 ISDN Digital Modem xxxx: V x.xx  
7607  
OK  
In the first line, x designates the country or region of operation and the firmware version  
number. The second line is the firmware checksum (which changes based on your firmware  
version).  
Communication Speed Setup  
Make sure the program is set up to communicate with the COM port that is connected to the Model  
XM128 modem. In most cases, when the terminal program is active and ready to communicate  
with the connected port, the DTR signal is activated and the DTR LED lights. If the DTR LED is  
off, check the terminal program settings.  
The communication speed can be set between 110 bits per second (bps) and 460.8 bps, but 115.2  
bps is a good default value. The Model XM128 modem automatically adjusts its speed to match  
the communication speed you set.  
4-4  
Configuration  
 
         
Reference Guide for the Model XM128 ISDN Digital Modem  
Switch Type Setup for North America  
In North America, the popular types of switches are AT&T 5ESS, Northern Telecom DMS100,  
and Siemens EWSD. All of these switches run software that either conforms to the National  
ISDN-1 standard or a custom version. The Model XM128 modem supports the six different  
combinations listed in Table 4-4. The value for n in the ATPn command is shown in the AT  
command column. The ATPn command programs the D channel protocol so that the Model  
XM128 modem works with the type of switch that is connected to your ISDN line.  
Table 4-4.  
Switches supported by the Model XM128 modem  
ISDN network switch  
Switch version  
AT command  
Number of SPIDs  
AT&T 5ESS network switch  
Point-to-point Protocol  
Point-to-multipoint Protocol  
Point-to-multipoint Protocol  
National ISDN-1  
ATP4  
ATP5  
ATP6  
ATP1  
ATP2  
ATP0  
ATP1  
ATP2  
ATP1  
ATP2  
ATP1  
ATP2  
0
1
2
1
2
2
1
2
1
2
1
2
National ISDN-1  
NT DMS 100 network switch  
Custom  
National ISDN-1  
National ISDN-1  
Siemens EWSD network switch National ISDN-1  
National ISDN-1  
Other  
National ISDN-1  
National ISDN-1  
To set your switch type, use AT commands (examples given are if your switch type is DMS 100  
with Custom Protocol) and follow these steps:  
1. Type ATP0 and press [Enter].  
You should receive the following response:  
OK  
Switch Type: Northern Telecom DMS 100  
2. Type AT&WZ and [Enter] to save the settings.  
You should receive the following response:  
OK  
Configuration  
4-5  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
SPID Setup for North America  
SPID numbers are needed unless your switch type is AT&T 5ESS with Point-to-Point Protocol.  
The ISDN switches use SPID numbers to represent the subscribed network services. Each SPID  
corresponds to one terminal end point identifier. Different switches might provide different rules  
for the SPID number format. You should get the SPID number from your local telephone company.  
To program your SPID number(s), use AT commands (n is the SPID provided by your telephone  
company) and follow these steps:  
1. Type ATSPIDO=n and [Enter].  
You should receive the following response:  
OK  
SPID Correct!  
It might take up to 30 seconds for the response. This response indicates that the SPID number  
was accepted. If a second SPID is required, go to step 2.  
2. Type ATSPID1=n and [Enter].  
You should receive the following response:  
OK  
SPID Correct!  
An error condition is present and it indicates that an incorrect SPID number was entered if you  
receive the following response:  
OK  
SPID Error!  
A general failure is indicated if the ISDN line is not connected to your Model XM128 modem or  
if you select the wrong switch. The SPID number was not verified if you receive the following  
response:  
OK  
The D LED lights when the SPID(s) are entered and verified. If you are not able to get the SPID(s)  
to accept correctly, recheck all cable connections before verifying the number(s) with your  
telephone company and reentering them again. If the D LED still does not light, the telephone  
company should make sure the line you ordered has been correctly set up.  
4-6  
Configuration  
 
   
Reference Guide for the Model XM128 ISDN Digital Modem  
Entering DNs  
You will need to enter the phone numbers given to your ISDN line. The phone numbers will be  
cleared whenever the switch type is changed.  
1. Type ATDN0=n and [Enter].  
Where n is the 7-digit phone number.  
You should receive the following response:  
OK  
2. Type ATDN1=n [Enter].  
Where n is the second 7-digit phone number.  
You should receive the following response:  
OK  
3. Type AT&W0Z0 and [Enter] to save the settings.  
You should receive the following response:  
OK  
Setup for Europe and the United Kingdom  
To configure your Model XM128 modem for Europe and the United Kingdom, follow these steps:  
1. Type the command AT&ZOI= and the ISDN telephone number to assign the outgoing  
telephone numbers.  
For example, AT&ZO=5551111  
2. Press [Enter].  
3. Type the command AT&ZOA= and the outgoing telephone number for PHONE 1.  
For example, AT&ZOA=5552222  
4. Type the command AT&ZOB= and the outgoing telephone number for PHONE 2.  
For example, AT&ZOB=5553333  
5. Assign a protocol using the commands in Table 4-5 to configure the B channel protocol.  
Configuration  
4-7  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
Table 4-5.  
AT commands for setting protocols  
Protocol  
AT command  
X.75  
ATB00&O2  
V.110 user rate - 38400 bps  
ATB18&O2  
ATB20&O2  
ATB40&O2  
V.120  
PPP  
For example, if the protocol you want is PPP, type the command ATB40&O2. For other X.75  
or V.110 protocol options, refer to Appendix C, “AT Command Set Reference.”  
6. Assign the appropriate MSN telephone numbers, using the AT commands in Table 4-6.  
Table 4-6.  
AT commands for setting MSN  
Multiple subscriber number  
AT command  
X.75 telephone number  
V.110 telephone number  
V.120 telephone number  
PPP telephone number  
AT&ZI0=telephone number  
AT&ZI1=telephone number  
AT&ZI2=telephone number  
AT&ZI3=telephone number  
ISDN Data (Protocol autodetection) AT&ZI4=telephone number  
PHONE 1  
PHONE 2  
AT&ZI6=telephone number  
AT&ZI7=telephone number  
For example, to assign an MSN number for a V.120 call, type the command AT&ZI2=5553434.  
7. Type the AT command AT&W0Z0 to store the information into NVRAM.  
4-8  
Configuration  
 
       
Chapter 5  
Async to Sync PPP  
This chapter describes the application of asynchronous to synchronous HDLC conversion.  
Internet and Remote Access PPP and SLIP  
More and more Internet Service Providers are offering their services through dial-up ISDN lines  
for higher data bandwidth. The equipment used by your service provider frequently consists of  
ISDN LAN routers which, unlike a digital modem, do not have asynchronous capability. For this  
reason, terminal adapters that support only V.120 or asynchronous protocol do not work with this  
type of equipment.  
The Model XM128 modem converts the asynchronous data it receives from your computer to  
synchronous format in order to communicate with ISDN LAN routers. We call this process  
asynchronous to synchronous HDLC conversion or Async to Sync PPP (Point-to-Point Protocol)  
or Async to Sync Serial Line Internet Protocol (SLIP) protocol.  
Making Async to Sync PPP and SLIP calls  
In order to communicate with an ISDN LAN router (from vendors such as Ascend and Cisco), set  
the Model XM128 modem B channel protocol to one of the following:  
ATB40<Enter> (HDLC PPP)  
or  
ATB41<Enter>(HDLC SLIP)  
You should also set the DTE speed based on the bandwidth that the switches support.  
Async to Sync PPP  
5-1  
 
           
Reference Guide for the Model XM128 ISDN Digital Modem  
Most of the time, you only use this protocol for making calls to remote sites with ISDN LAN  
Routers. If the remote access site you are calling uses a Terminal Adapter such as the  
Model XM128 modem, you can use V.120, as it provides data compression.  
Before making the call, check which protocol is set for the ISDN mode using the &V command to  
view the settings.  
When you are ready to view the settings type:  
AT&V<Enter>  
The Model XM128 modem modem responds:  
Current Settings...  
Switch Type: Northern Telecom DMS  
ISDN Outgoing Service: PPP Async-to-Sync Conv 64K  
If the settings displayed match your current setup, you are ready to place the call.  
When you are ready to place the call type:  
ATDI<remote_access_number><Enter>  
The Model XM128 modem responds:  
Connect 115000/64000 PPP/None  
Keeping a Line Connection During Idle Time  
If you are using PPP to access a server the server probably has a watchdog timer to monitor the  
line activity. If the idle time exceeds some time interval (usually 1 minute), the server releases the  
connection for other clients to dial in. Users may suffer some inconvenience because you have to  
dial to the server again and repeat the login procedure when disconnected. The value in register  
S124 (in seconds) is used as the idle time gauge. If the idle time exceeds this guarding period, the  
Model XM128 modem sends out a dummy PPP packet to the server to keep it from disconnecting  
the line.  
Example: If the server you are calling disconnects after 1 minute of inactivity, issue the following  
command before connecting:  
ATS124=59<Enter> (send dummy PPP packet after 59 seconds of inactivity)  
Setting S124=0 disables this function.  
5-2  
Async to Sync PPP  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
Answering Async to Sync PPP calls  
There is no need to configure the ISDN mode to the protocol of an incoming call. If it is set to  
auto-answer or an answering command is issued, the Model XM128 modem determines the  
correct protocol to use by examining the data coming in from the remote site. One exception is  
when the ISDN data call is carried through a Speech bearer. In this case you would need to set up  
an MSN for the phone number of the calling party. To do this, use the command AT&ZI3=xxx;  
where xxx is the number from which the call originates.  
For the Model XM128 modem to automatically answer incoming calls, you need to set S0 to a  
value greater than 0 (i.e. ATS0=1). The Model XM128 modem answers the call and uses  
asynchronous to synchronous conversions to and from the DTE. If S0 is not set (S0=0), the DCE  
reports RING and also makes an audible ring notification.  
Multilink PPP  
Multilink PPP (MPPP) is a protocol that allows virtual bundling of the two B channels allowing  
connection speeds of 128Kbps. MPPP support is a standard feature of the Model XM128 modem.  
Making a call using Multilink PPP  
A Multilink PPP connection is initiated at the calling site when ATB40 (B channel protocol HDLC  
PPP) has been selected and the Multilink PPP mode has been enabled by an AT&Jn command:  
AT&J0 (disables Multilink PPP)  
AT&J1 (enables Multilink PPP in answer mode only)  
AT&J2 (enables Multilink PPP in call mode only)  
AT&J3 (enables Multilink PPP in both call and answer modes)  
By default, the Model XM128 modem dials the same number for both Multilink PPP connections.  
If the destination you are dialing requires two different telephone numbers to establish a two  
channel Multilink PPP connection, then the following command can be used:  
ATDIphone_number_1+phone_number_2  
The phone numbers of the destination are determined by the commands: phone_number_1 and  
phone_number_2 are the phone numbers of the destination.  
If the destination refuses the Multilink PPP during the Link Control Protocol (LCP) negotiation, a  
single B channel PPP connection is established. The connection message is the same whether the  
Multilink PPP connections have been established or not.  
Async to Sync PPP  
5-3  
 
                 
Reference Guide for the Model XM128 ISDN Digital Modem  
Dialing Pre-stored Phone Numbers  
The ATDSn command, n=0,1,..,39, dials the (n+1)th phone number twice for both of the Multilink  
PPP connections. The command ATDSn+Sm, (n and n=0,1,...,39) dials the (n+1)th phone number  
for the first connection and the (m+1)th phone number for the second connection.  
Example: ATDIS0+S1 [Enter] dials the number stored in location 0, and the number stored in  
location 1 for the MPPP connection.  
Endpoint Discriminator  
The Endpoint Discriminator option represents identification of the system transmitting the packet.  
This option advises a system that the peer on this link could be the same as the peer on another  
existing link. Some Multilink PPP implementations require the use of the Endpoint Discriminator  
option.  
The Endpoint Discriminator consists of two components: Class and Address.  
The Class field is one octet as stored in S-register S85 and indicates the identifier address space.  
Table 5-1 lists the valid values of the S85 register.  
Table 5-1.  
S85 register values  
Description  
Value  
0
1
2
3
4
5
Null Class (by default).  
Internet Protocol (IP) Address  
IEEE 802.3 Globally Assigned MAC Address.  
Locally Assigned Address.  
PPP Magic-Number Block.  
Public Switched Network Directory Number.  
The Endpoint Discriminator Address field is of variable length from 0 to 20 octets and can be  
assigned by the ATEPD command:  
ATEPD = <Octet_1,Octet_2,Octet_3,..,Octet_n>  
5-4  
Async to Sync PPP  
 
               
Reference Guide for the Model XM128 ISDN Digital Modem  
Each Octet_i is in the range from 0 to 255. The angle brackets (<) and (>) are part of the this  
command. The command ATEPD? can be used to view current setting of the Endpoint  
Discriminator Address.  
Note: The Endpoint Discriminator option is not required in most cases, thus users don't  
have to change the default settings. The system administrator of your corporate or the  
Internet service provider provides these values if the Endpoint Discriminator option is  
required.  
Call Bumping Dynamic Channel Allocation  
When call bumping, Dynamic Channel Allocation (DCA) is enabled (by default), you can place or  
answer a voice call (and only one) from a device that is attached to one of the phone ports. The call  
can be placed while a Multilink PPP call is active. The Model XM128 modem automatically  
removes one of the Multilink PPP connections and uses it for the voice call. When the voice call  
ends, the Model XM128 modem automatically reestablishes that channel for Multilink PPP  
operation. The call bumping DCA function is only effective when the Model XM128 modem is at  
the calling site (the client site). The following command can be used to select the DCA function:  
ATCE0 (disables call bumping)  
ATCE1 (enables call bumping by default)  
Async to Sync PPP  
5-5  
 
     
 
Chapter 6  
ISDN Overview  
This chapter covers the procedures for initiating and receiving calls over digital lines using your  
Model XM128 ISDN Digital Modem.  
Commands for Outgoing Calls  
The Model XM128 modem uses the following three modes to send communication over your  
ISDN network:  
ISDN data  
Analog port, PHONE 1 communication  
Analog port, PHONE 2 communication  
These modes are automatically switched based on the commands you issue. To understand this  
process, use your terminal program and proceed with the instructions explained in the following  
sections.  
Dialing Out Using ISDN Mode  
The command ATDI tells your Model XM128 modem that you want to make an ISDN data call  
and to therefore use the ISDN mode to call out. Enter:  
ATDI17142630398  
This command initiates an ISDN call.  
ISDN Overview  
6-1  
 
         
Reference Guide for the Model XM128 ISDN Digital Modem  
Dialing Out Using ISDN Mode Optional Speech Bearer Service  
The Model XM128 modem supports ISDN data utilizing Speech Bearer Service. To enable this  
function, you need to set S-register S83 bit 7 to 1 (ATS83.7=1). This function is useful in the areas  
where ISDN service providers charge lower usage rates for voice (speech) calls. To enable this  
function, enter:  
ATS83.7=1  
To disable it, enter:  
ATS83.7=0  
Dialing Out for Analog Adapter Port 1  
Using the A command following the ATD tells your Model XM128 modem to switch the call to  
analog adapter port PHONE 1, when dialing is complete. Enter:  
ATDA17146930762  
Note: You must have an analog modem connected to your plain old telephone service  
(POTS) port before you issue this command.  
Dialing Out for Analog Adapter Port 2  
Using the B command following the ATD tells your Model XM128 modem to automatically  
switch the call to analog adapter port PHONE 2, when dialing is complete. Enter:  
ATDB17146930762  
Manually Switching Communication Modes  
The manual switching function is necessary only if your communication software does not allow  
you to change your dial-up string.  
6-2  
ISDN Overview  
 
           
Reference Guide for the Model XM128 ISDN Digital Modem  
Conventional dialing commands ATD, ATDT, and ATDP, used by much of the existing  
communication software, can be mapped onto one of the new dialing commands according  
to the AT&O setting as shown in Table 6-1.  
Table 6-1.  
Dialing commands  
Dial string it maps to  
AT Command  
AT&O0  
AT&O2  
AT&O3  
ATD, ATDT, and ATDP are the same as ATDB.  
ATD, ATDT, and ATDP are the same as ATDI.  
ATD, ATDT, and ATDP are the same as ATDA.  
The factory default is AT&O2, which means that the Model XM128 modem selects ISDN data  
mode when you do not specify the communication mode to use (that is, ATD or ATDT).  
Placing the Call  
To initiate a call, choose the proper communication mode and configure the mode according to  
the bearer service (or protocol) you want to use. Table 6-2 contains some simple commands that  
are useful when placing a call.  
Table 6-2.  
Command  
Call placing commands  
Description  
ATBnn  
ATDL  
Changes ISDN B channel protocol setting  
Redials the last dialed telephone number  
ISDN Overview  
6-3  
 
             
Reference Guide for the Model XM128 ISDN Digital Modem  
Commands for Incoming Calls  
When a call comes in, the call is carried by one of the following protocols:  
V.120  
HDLC PPP, MPPP, or SLIP  
V.110  
X.75  
Or the call may be initiated by an analog device.  
This section provides some general guidelines for setting up the Model XM128 modem for call  
answer handling. Be aware that the modem does not automatically answer a call unless S-register  
S0 is set to a value greater than 0 (zero). If S-register S0=0, the modem only reports RING to your  
terminal program. It can also respond with an audible tone that allows you to decide whether or not  
you should take any action.  
When an ISDN data call comes in, the Model XM128 modem tries to negotiate a connection using  
the proper ISDN protocol. When an analog call comes in, the modem sends the call to the analog  
port as the factory default, PHONE 1, and then PHONE 2.  
Digital Data  
The Model XM128 modem currently supports Circuit Switched Data (CSD) for ISDN data  
applications. The CSD protocols supported by the Model XM128 modem include: PPP, MPPP,  
V.120, X.75, and V.110. PPP is the most popular protocol used in North America; it is used by  
most of the Internet service providers. After the Model XM128 modem answers a call, it examines  
the incoming data to determine which protocol to use and automatically switches to that mode.  
This process occurs transparently to the user. The Model XM128 modem is able to auto-switch for  
PPP, MPPP, V.120, X.75, and V.110 protocols over speech channel. In most cases, you can rely on  
the auto-switching feature for your applications. If you need more specific settings for answering  
calls, refer to “Answering a Call Using MSN” on page 5-5.  
6-4  
ISDN Overview  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
Determining the Packet Length  
The user’s information is sent on a frame-by-frame basis for V.120 and X.75, sometimes called  
packetized. The maximum frame length on the sending side should not exceed the maximum  
frame length that the receiving side allows. Sometimes this information is exchanged during  
handshaking. However, few manufacturers, if any, have implemented this mechanism.  
If the sending side sends packets greater than what the receiving side allows, the receiving side  
discards the frame and replies with a Frame Reject Frame (FRMR). The FRMR indicates that the  
information received is too long. Both sides then reset their link layer negotiation and send the  
frame again. Usually this process repeats until the call gets disconnected.  
The Model XM128 modem has a fixed maximum receiving frame size of 2048 octets, which is  
larger than most devices can support. The default maximum sending frame size is 252 octets for  
V.120 and 2048 for X.75. If you need to change the maximum sending frame size, the ATCL  
command is used.  
To change the maximum sending frame size, use the following commands and follow these steps:  
1. Enter ATCL252 (set the frame size to 252 octets, user value between 1 and 2048).  
You should receive this message:  
OK  
2. Enter ATCL? (to inquire about the current setting of the packet length).  
You should receive this message:  
Maximum user data length in a packet (byte) : 252  
ISDN Overview  
6-5  
 
   
Reference Guide for the Model XM128 ISDN Digital Modem  
Answering a Call Using MSN  
When answering an incoming call, the call is first identified if the caller number matches the  
Multiple Subscriber Number (MSN) settings.  
The MSN supplementary service enables multiple ISDN numbers to be assigned to a single  
ISDN BRI line. It allows the caller to select, through the public network, one or more distinct  
terminals from a variety of terminal choices. The Model XM128 modem supports many different  
communication protocols and two analog adapters. Table 6-3 shows the commands used to assign  
each of the ports to an ISDN number.  
Table 6-3.  
Commands for assigning ISDN numbers  
Command  
&ZI0=s  
&ZI1=s  
&ZI2=s  
&ZI3=s  
&ZI4=s  
Description  
Assigns the MSN phone number for X.75  
Assigns the MSN phone number for V.110  
Assigns the MSN phone number for V.120  
Assigns the MSN phone number for PPP, MPPP  
Assigns the MSN phone number for ISDN data,  
protocol auto-detection  
&ZI5=s  
&ZI6=s  
&ZI7=s  
Assigns the MSN phone number for PPP, MPPP  
Assigns the MSN phone number for Phone 2  
Assigns the MSN phone number for Phone 1  
The command AT&ZI? can be used to display the MSN numbers. The factory default for these  
numbers is UNASSIGNED.  
6-6  
ISDN Overview  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
If an incoming setup message is offered with addressing information (that is, the appropriate part  
of the Called Party Number), this address is compared with the MSN numbers assigned by the  
AT&ZIn=s commands. The call is accepted using the specific protocol if the assigned number of  
this protocol matches the received Called Party Number.  
Note: You are not required to enter the complete numbering string for the AT&Z  
command. The last few distinguishable digits are enough for the XM128 to make the  
decision. Two phone number strings are said to be matched if their least significant n  
digits are identical, where n is the number of digits in the shorter string.  
The called party subaddress information within the incoming setup message can also be  
used to select the protocols and/or analog ports. In normal conditions, called party subaddress  
information is not used by the Model XM128 modem to select the protocols or services, but only  
indicates the subaddress (if any) to the DTE. Refer to Chapter 11 for more detailed information.  
Data over Speech Channel  
If you are expecting ISDN data calls through Speech (Voice) channel, you would need to set up  
MSN for it. If no MSN entries are found in MSN ISDN data lists, all speech (voice) calls are sent  
to either PHONE 1 jack or PHONE 2 jack. The entry to use would depend on the type of data call  
that you are expecting. If you expect only PPP type of calls, you should enter the number that the  
remote user used to dial in to entry #3 (AT&ZI3=xxx) or entry #5 (A&ZI5=xxx). After this  
number is set, when the caller dials in to this number, the Model XM128 modem attempts to use  
PPP protocol to handshake with this remote user. This handshake takes place whether the setup  
message from the switch indicates an ISDN data call or a speech (voice) call.  
Best-effort Call Answering  
If some numbers have been set using &ZIn command (as can be seen by the AT&ZI? command)  
and they are not matched with the address of the incoming call, the Model XM128 modem, by  
default, ignores the call because it may be intended for other devices that share the same S/T  
interface (S0 bus) with the Model XM128 modem.  
ISDN Overview  
6-7  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
If you want the Model XM128 modem to answer inbound calls using all possible protocols, refer  
to Table 6-4 for the commands used to set the best-effort call answering bit.  
Table 6-4.  
Command  
Best-effort call answering bit commands  
Function  
ATS119.3=0 Answer call only when number matched (by default)  
ATS119.3=1 Best-effort call answering  
Ambiguity Resolution Switch for Voice Calls  
For a speech or voice-band-data call, if the &ZI number assignment can tell which of the analog  
adapters is being addressed, then the call is delivered to the proper destination. Sometimes,  
however, ambiguity of address matching may exist. This ambiguity may exist if the &ZIn numbers  
of the various protocols are either unassigned or not matched or the address information is absent  
in the incoming setup message. In this case, users may want to set answering priority to an analog  
port. The AT&Ln command sets the address ambiguity resolution flag as follows:  
AT&L0  
The analog adapter 1 has the higher priority to answer a voice or voice-band-analog-data call.  
If the analog adapter 1 is busy, the call is routed to the analog adapter, PHONE 2.  
AT&L1  
The analog adapter 2 has the higher priority to answer a voice or voice-band-analog-data call.  
If the analog adapter 2 is busy, the call is routed to the analog adapter, PHONE 1.  
Multi Auto-Answering of Data Calls  
When an ISDN data call comes in, the Model XM128 modem can determine the protocol to be  
used in one of two ways.  
One is way is through the information conveyed by the setup message. For DSS1, this information  
includes the bearer capability, low-layer compatibility, or high-layer compatibility information  
elements; for 1TR6, it includes the Service Indicator as well as an Additional Octet of the Service  
Indicator.  
The other way is by the Multi Auto-answering process. The Model XM128 modem determines  
the protocol by monitoring the B channel signal sent by the calling site.  
With either method, the data call can be identified by the modem to be X.75, V.110, V.120,  
or PPP, MPPP Async-to-Sync conversion.  
6-8  
ISDN Overview  
 
             
Reference Guide for the Model XM128 ISDN Digital Modem  
If the address-matching process is again unable to tell which protocol to use, the Model XM128  
modem goes into the Multi Auto-answering Routine by examining the B channel data pattern and,  
hence, determining the protocol to use.  
When alerted, the Model XM128 modem sends a RING message to the DTE in the following  
format:  
RING  
FM:17145522863TO:17142630398  
Understanding ISDN Communication Protocols  
Table 6-5 shows the specifications of different ISDN protocols.  
Table 6-5.  
Parameter  
ISDN protocol specifications  
V.110  
V.120  
X.75  
Layer 1  
80 Bits Framing  
HDLC  
LAPD  
V.120  
Yes  
HDLC  
Layer 2  
None  
None  
No  
LAPB Transparent  
ISO8208T.70 NL  
Yes  
Layer 3  
Error Control  
V.42bis  
No  
Yes  
Yes  
Async or Sync if used  
with V-Series DTE  
Async Only  
Async Only  
Async Only  
Bundle  
No  
Yes  
Yes  
Max. Line Speed  
Async: 38.4 Kbps  
Sync: 64 Kbps  
64 Kbps  
128 Kbps  
64 Kbps  
128 Kbps  
AT-Command  
Configuration  
ATB10  
ATB20  
ATB00 Transparent  
ATB01: T.70 NL  
ISDN Overview  
6-9  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
V.110 ISDN Communications  
This section describes how to set up and configure your Model XM128 modem with the V.110  
Protocol.  
Answering a V.110 Call  
After you set the proper V.110 communication mode, there is no need to configure the ISDN mode  
to the protocol of an incoming call. If the device is set to auto-answer, the Model XM128 modem  
determines the correct protocol to use by examining the data coming in from the remote site.  
Otherwise, this determination takes place after an answering command is issued.  
One exception to this process is when the ISDN data call is carried through speech bearer. In this  
case, you need to make an MSN entry for the phone number from which you are expecting the  
data-over-speech-bearer call to be coming for X.75 protocol. Use AT&ZI1=n. Refer to “Data over  
Speech Channel” on page 6-7 for details.  
To allow the Model XM128 modem to answer the incoming call, you need to set S0 to a value  
greater than 0 (in other words. ATS0=1). The Model XM128 modem answers the call and uses  
asynchronous to synchronous conversions to and from the DTE. If S0 is not set (S0=0), the DCE  
reports RING and also makes an audible ring notification.  
Making a V.110 Call  
Before an ATDIxxx command is issued to dial out, make sure that your Model XM128 modem is  
in the asynchronous mode (AT&M0). Use the commands in Table 6-6 to configure V.110 ISDN  
communication.  
Table 6-6.  
V.110 configuration commands  
Description  
AT Command  
ATB10  
ATB13  
ATB14  
ATB15  
ATB16  
ATB17  
ATB18  
ATB19  
User rate follows DTE speed  
User rate = 2400bps  
User rate = 4800bps  
User rate = 9600bps  
User rate = 14400bps  
User rate = 19200bps  
User rate = 38.4 Kbps  
User rate = 57.6 Kbps (Japanese version only)  
6-10  
ISDN Overview  
 
             
Reference Guide for the Model XM128 ISDN Digital Modem  
The highest asynchronous V.110 user rate depends on bit 4 of S119 as follows:  
S119.4=0 (19.2 Kbps)  
S119.4=1 (38.4 Kbps for areas other than Japan)  
S119.4=1 (57.6 Kbps for Japanese version)  
If the DTE speed is higher than what has been set, the user rate in Table 6-6 is used.  
The X bits in the 80-bit frame are used for remote flow control.  
V.120 ISDN Communications  
This section describes how to set up and configure your Model XM128 modem with the V.120  
ISDN protocol. Refer to Table 6-5 on page 6-9 for the ISDN protocol specifications.  
Selecting V.120 for European ISDN (DSS1) Switch  
With European ISDN, V.120 is an option in the bearer capability (BC) information element, which  
is a mandatory information element in the setup message. Although we can specify V.120 in the  
low-layer compatibility (LLC) information element, some switches just do not deliver the LLC.  
Other switches do deliver the LLC, but the V.120 selection is discarded midway.  
If the called modem does not get any B channel protocol information from the incoming setup  
message and the remote device is a NETGEAR ISDN device, the Model XM128 modem can  
identify the V.120 protocol automatically with the Multi Auto-answer Routine. Otherwise, the  
handshake fails.  
Selecting V.120 for German National ISDN (1TR6)  
With a 1TR6 switch, data connections are achieved by setting the Service Indicator to 7  
(Daten_bertragung 64Kbps) and using the Additional Information octet to select B channel  
protocols. Because there is no predefined code for asynchronous V.120, the Model XM128 modem  
uses the synchronous V.120 code to fill in the additional information octet. This approach might  
not work all the time.  
ISDN Overview  
6-11  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
Answering a V.120 Call  
In most cases, there is no need to configure the Model XM128 modem to properly answer calls.  
The Model XM128 modem decides which protocol to use by detecting the type of data that is  
received. You only need to set S0 to greater than or equal to 1 in order for the modem to  
automatically answer an incoming call. If S0=0, the DCE simply reports RING to your terminal  
and sounds a ring notification.  
One exception to this is when the ISDN data call is carried through speech bearer. In this case,  
you would need to make an MSN entry for the phone number from which you are expecting the  
data-over-speech-bearer call to be coming. For V.120 protocol, use AT&ZI2=n. Refer to “Data  
over Speech Channel” on page 6-7.  
Making a V.120 Call  
Some switches transmit all network signals through the D channel (out-of-band signaling),  
allowing both B channels to be used exclusively for your communication purposes. This  
arrangement allows for throughput of 64 Kbps per channel. However, not all switches support  
out-of-band signaling at this time. For switches that do not support out-of-band signaling, network  
signals are transmitted through the B channels, which reduces the bandwidth to 56 Kbps.  
When making a V.120 call, be sure that the communication supports out-of-band signaling. If it  
does not support out-of-band signaling, you need to set your Model XM128 modem to 56K mode  
using the AT&E1 command (AT&E0 to set it back to 64K mode). If your modem is on the  
receiving end, you can keep the setting at AT&E0 (64K data mode). The modem automatically  
switches between the two speeds in answer mode.  
Configuring the V.120 Mode  
To configure for a 56K V.120 call, use the following commands:  
1. Enter ATB20 (Select V.120 for communication).  
Model XM128 modem should respond with:  
OK  
2. Enter AT&E1 (Select 56K data mode).  
Model XM128 modem should respond with:  
OK  
6-12  
ISDN Overview  
 
         
Reference Guide for the Model XM128 ISDN Digital Modem  
Now you are ready to dial the phone number. If you need to save the setting into NVRAM, use the  
following commands and follow these steps:  
1. Enter AT&W0 (save the settings to profile 0) [Profiles available: 0-3].  
Model XM128 modem should respond with:  
OK  
2. Enter ATZ0 (save stored settings as the power on settings to profile 0)  
[Profiles available: 0-3].  
Model XM128 modem should respond with:  
OK  
All of the above commands can be simplified by combining all the commands onto one line  
(for example, AT&B20&E1&WZ0).  
Dialing in V.120 Mode  
Finally, use the ATDn command to make the call (n is the phone number you want to dial). Once  
the connection is made, you should see the following connect messages:  
CONNECT 115200/V120 56000/LAPD  
This message indicates that the connection is made with the following specifications:  
DTE speed of 115.2 Kbps  
Protocol V.120  
Data speed of 56 Kbps  
Error Control LAPD  
Making a Bundled Call with V.120  
A bundled V.120 connection is initiated at the calling site when ATB20 (B channel protocol V.120)  
has been selected and the channel bundling mode has been enabled by an AT&J3 command. The  
channel bundling command (AT&J3) must be set on both the calling and receiving sides;  
otherwise, a single channel connection is made.  
To set up your Model XM128 modem to make a bundled V.120 connection, follow these steps:  
1. Enter ATB20 (set B channel protocol to V.120).  
2. Enter AT&J3 (set the Model XM128 modem to make a bundled call).  
ISDN Overview  
6-13  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
3. Enter AT&WZ (if you want to save the setting).  
After these commands are entered, the ATD command generates two consecutive setup  
messages to invoke bundle initiation.  
For the Northern Telecom switch, each BRI phone number can be called only once at any  
given time. So if you dial this number, it reports busy to any other incoming calls. In order to  
use two B channels for aggregation, you must place two calls with different phone numbers.  
To place these calls, separate the two numbers with a plus (+) sign after the ATD command.  
For bundling calls with the Northern Telecom switch, enter the following commands:  
ATDI[phone_number_1]+[phone_number_2]  
4. Press [Enter].  
The answering Model XM128 modem determines that the call is a bundle request: when AT&J3 is  
set and two consecutive setup messages are received. The two data calls are established as one  
message. The phone company’s ISDN line splits it off into two messages. That is, the ISDN  
network treats the messages as two independent calls. Finally, the receiving side receives one  
bundled message into the computer’s serial port.  
The success of a bundle connection initiation is indicated by the connect message reported to the  
DTE. The following two examples are of connect messages:  
CONNECT 115200/V120M 128K/LAPD  
or  
CONNECT 115200/V120M 128K/LAPD/V42b (with data compression)  
If you are not using American ISDN, you have a choice between Multiple Link Protocol (MLP) or  
cFos channel bundling (CCB), two bundle protocols. You can set it by the following commands:  
ATS100=0  
ATS100=1  
(for MLP channel bundling)  
(for CCB channel bundling)  
Identifying Your Line Provisioning  
For bundled connections, the two B channels of your ISDN line must be able to handle data circuit  
switch connections with unrestricted 64 Kbps or 56 Kbps line speeds. Two separate data calls can  
be established consecutively.  
6-14  
ISDN Overview  
 
 
Reference Guide for the Model XM128 ISDN Digital Modem  
128 Kbps Speeds  
BRI ISDN consists of three (2B+D) logical channels. Each B channel can be used independently  
for a dial-up connection running at 56 Kbps or 64 Kbps (bits per second).  
The two B channels can be used together for a single data connection to provide 112K (with  
In-Band Signaling) or 128K (when Out-of-Band Signaling is used). It is called a Bundle  
Connection (different from BONDING).  
The type of channel bundling described in the V.120 section is supported only between the  
following NETGEAR products: Model XM128 modem. Dialing Prestored Phone Numbers  
Use ATDSn, n=0,1,...,39, to dial the (n+1)th phone number twice for both the bundle connections.  
Use ATDSn+Sm, (n and n=0,1,...,39) to dial the (n+1)th phone number for the first connection and  
the (m+1)th phone number for the second connection.  
For example, ATDIS0+S1[Enter] dials the number stored in location 0, and the number stored in  
location 1 for the bundle connection.  
Error Correction and Data Compression with V.120  
With V.120, the default setting is for Link Access Protocol Digital (LAPD) error correction only.  
No data compression is negotiated. The following AT commands are used to switch the V.42bis  
data compression on or off for ISDN data calls when using V.120 protocol:  
AT&K44 (enable V.42bis on ISDN call)  
AT&K00 (disable V.42bis on ISDN call)  
With the &K44 setting, the Model XM128 modem tries to connect using V.42bis data  
compression. If the remote device does not support V.42, then LAPD error correction can be used.  
When a connection is made using V.42bis compression, the following connect message is  
displayed:  
CONNECT 115200/V120 56000/LAPD/V42b.  
It takes extra time for the calling ISDN device to negotiate V.42bis. If you know in advance that the  
called site has no V.42bis capability, it would be better to issue the AT&K00 command beforehand  
in order to get a quick connection.  
V.42bis is an international data compression standard commonly used in modem communications.  
This standard provides real-time data compression. The NETGEAR expertise in data compression  
has been brought into its ISDN applications, which are much higher in speed than modem  
communications.  
ISDN Overview  
6-15  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
Because the V.42bis algorithm needs an error-free transmission channel between the compression  
and decompression processes, it can only work with a protocol that has error control competence.  
The X.75 and V.120 protocols can be used together with V.42bis data compression. The V.110  
protocol, on the other hand, is just an R-interface layer 1 adaptation protocol without error-control  
and is thus inadequate for V.42bis.  
X.75 ISDN Communications (Europe)  
This section describes how to set up and configure your Model XM128 modem with X.75  
protocols. Refer to Table 6-5 for the X.75 protocol specifications for Europe.  
The X.75 protocol was originally designed for packet-switched signaling systems in public  
networks to provide data transmission services. Now, however, it is also used as the link layer for  
telematic services (as defined in T.90) in ISDN. These services include both the ISDN  
circuit-switched mode (DTE-DTE communication) and the ISDN packet-switched mode  
(DTE-DCE communication).  
Answering an X.75 Call  
There is no need to configure the ISDN mode to the protocol of an incoming call. The Model  
XM128 modem is able to determine the correct protocol to use by examining the data coming in  
from the remote site. Protocol determination takes place if the device is set to auto-answer or after  
an answering command is issued.  
One exception to this process is when the ISDN data call is carried through speech bearer. In this  
case, you need to make an MSN entry for the phone number from which you are expecting the  
data-over-speech-bearer call to be coming for the X.75 protocol. Use AT&ZI0=n. Refer to “Data  
over Speech Channel” on page 6-7 for further information.  
To allow the Model XM128 modem to answer the incoming call, you need to set S0 to a value  
greater than 0 (for example, ATS0=1). The Model XM128 modem answers the call and uses  
asynchronous-to-synchronous conversions to and from the DTE. If S0 is not set (S0=0), the DCE  
reports RING and also makes an audible ring notification.  
Making an X.75 Call  
The default data protocol of the Model XM128 modem is ATB20 (V.120). the X.75 protocols can  
be chosen using the following AT commands:  
ATB00  
ATB01  
(for X.75 with transparent layer 3)  
(for X.75 with T.70 NL)  
6-16  
ISDN Overview  
 
           
Reference Guide for the Model XM128 ISDN Digital Modem  
The ATB0x commands not only specify the outgoing protocol, but also set the default layer 3  
for an incoming X.75 call without layer 3 information. It is important for both ends of an X.75  
connection to execute the same preassigned layer 3 protocol because it reduces the chance of  
the Model XM128 modem making the wrong protocol selection.  
For European ISDN (DSS1), the low-layer compatibility (LLC) information element in the setup  
message can be used to specify the layer 3 protocol. Because this is an option for ISDN switches,  
some of the switches might not deliver the LLC information element to the remote end. There is no  
provision for 1TR6 switches to specify the layer 3 protocol for X.75 type of calls.  
Making a Bundled Call with X.75  
A bundle connection is initiated at the calling site by sending two consecutive setup messages  
to the network. The two setup messages are all the same except for the Call Reference values.  
AT&Jn can be used for bundle configuration as follows:  
AT&J0 (disables B channel bundling)  
AT&J1 (enables B channel bundling in answer mode only)  
AT&J2 (enables B channel bundling in call mode only)  
AT&J3 (enables B channel bundling in both call and answer modes)  
The bundle protocol can be selected as follows:  
ATS100=0 (MLP channel bundling)  
ATS100=1 (CCB channel bundling)  
If channel bundling is enabled, the ATDIs command generates two consecutive setup messages to  
invoke bundle initiation.  
For Northern Telecom ISDN, each BRI destination phone number can be called only once at any  
time. In order to use two B channels for aggregation, you must place two calls with different phone  
numbers. For this purpose, enter the following command:  
ATDIphone_number_1+phone_number_2  
If the called site receives two consecutive setup messages with the same calling party number and  
bearer capability (or origination address for and service indicator for 1TR6), then it is deemed as a  
bundle request. The two data calls are established following normal call control procedures. That  
is, the network treats them as two independent calls.  
ISDN Overview  
6-17  
 
   
Reference Guide for the Model XM128 ISDN Digital Modem  
The devices in the two sites then use X.75 Multiple Link Protocol or cFos channel bundling  
protocol to coordinate the two B channels. The former would need an overhead of 2 octets for each  
packet. The following is an example of the connect message reported to the DTE. The success of  
bundle connection initiation is indicated by this message:  
CONNECT 460800 / X.75M 128K / V42b  
If any B channel is unavailable in any site, the bundle initiation falls back to single channel  
connection. The following message may appear in this case:  
CONNECT 460800 / X.75 64000 / V42b  
Dialing Prestored Phone Numbers  
The 40 phone numbers stored in NVRAM can also be used to place a bundle call:  
ATDSn (dials the (n+1)th phone number twice for both the bundle connections; n=0 to 39)  
ATDSn+ (dials the (n+1)th phone number for the first connection and dials the (n+2)th phone  
number for the second connection; n=0-38)  
ATDSn+Sm (dials the (n+1)th phone number for the first connection and the (m+1)th phone  
number for the second connection; n=0-39; m=0-39)  
Invoking V.42bis Data Compression  
The following AT commands are used to switch the V.42bis data compression on or off for ISDN  
data calls when using X.75 or V.120 protocols:  
AT&K44 (enables V.42bis on ISDN call)  
AT&K00 (disables V.42bis on ISDN call)  
For X.75 to negotiate compression parameters with the remote ISDN terminal, you exchange XID  
frames before the Link Layer is established. The calling site sends an XID frame with V.42bis  
request to the called site. If the called site understands the meaning of this XID, it replies to an  
XID frame with a V.42bis request. If it is able to execute V.42bis, it ignores the XID or replies  
using an XID frame with a V.42bis reject or empty information field.  
The calling site assumes that the remote site is unable to execute V.42bis if it gets no reply for a  
period of time after sending the request XID. In this situation, normal connection without data  
compression is established.  
It takes about 2 seconds for the calling Model XM128 modem to send XID and wait until timing  
out. If you know in advance that the called site has no V.42bis capability, it would be better to issue  
the AT&K00 command beforehand in order to get a quick connection.  
6-18  
ISDN Overview  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
Although not defined in X.75, the XID frame is based on the encoding in ISO Standard 8885 and  
on being used in V.42/V.42bis. In addition to the compression parameters, XID can be used to  
negotiate such packet parameters as window or packet size.  
Bundle Connection with V.42bis Data Compression  
If both sites have set AT&K44 to enable V.42bis negotiation, XID frames can be exchanged  
through the main B channel, which corresponds to the call established by the first setup message.  
Only one data compression channel can be used in bundle connection, which means that the  
compression is done before packet disassembly and the decompression is done after packet  
assembly. The compression ratio of V.42bis is commonly recognized as up to 4:1 for text files. If  
the line speed is 128 Kbps, the DTE speed may reach 460 Kbps. This circumstance makes the  
normal RS-232 serial port of the DTE unsuitable for bundle applications. A special I/O card on the  
computer side is required in this situation for external models.  
ISDN Overview  
6-19  
 
 
 
Chapter 7  
Advanced ISDN  
This chapter provides information about using advanced ISDN for the Model XM128 ISDN  
Digital Modem.  
Call Control for DSS1  
In order to initiate a Digital Subscriber Signaling #1 (DSS1) ISDN call, two information elements  
are necessary:  
The bearer capability element indicates what kind of bearer service is desired. It is also used  
for compatibility checking in the addressed entity.  
The called party number element provides necessary information for the telephone company  
central office (CO) to direct the call to the destination.  
The following optional information elements are also pertinent to call control:  
High-layer compatibility  
Low-layer compatibility  
Calling party number  
Called party number  
Calling party subaddress  
Called party subaddress  
Advanced ISDN  
7-1  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
Control of Outgoing Service Indicator  
The high-layer compatibility and low-layer compatibility information provides a means for  
compatibility checking by the called party. This information is transferred transparently by the  
ISDN network between the call-originating entity (for example, the calling user) and the addressed  
entity.  
The outgoing high-layer compatibility can be controlled by setting the value of S-register  
S(108+n) as follows:  
n=0 (S108) setting for analog adapter 2  
n=2 (S110) setting for ISDN data calls  
n=3 (S111) setting for analog adapter 1  
Table 7-1 lists the S-register values and their functions.  
Table 7-1.  
S(108+n=)  
S-register values and functions  
Function  
0
No high-layer compatibility info element sent (default)  
Telephony  
1
4
Facsimile Group 2/3  
40  
49  
50  
Telex service (Rec. F.220)  
Telex service (Rec. F.200)  
International internetworking for video services (Rec.  
F.300 and T.110)  
53  
56  
Telex service (Rec. F.60)  
Message Handling Systems (MHS)  
(Rec. X. 400 series)  
65  
OSI application (Rec. X.200 series)  
Example: ATS111=4 sets fax compatibility message for analog port 1.  
7-2  
Advanced ISDN  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
Bearer capability and low-layer compatibility information elements are determined when you  
configure the B channel protocols using the ATBnn command. The outgoing low-layer  
compatibility information element can be turned on or off by setting the S80 bit n as follows:  
n = 4 for analog adapter 2  
n = 6 for ISDN data calls  
n = 7 for the analog adapter 1  
Table 7-2 lists the commands for enabling and disabling outgoing low-layer compatibility.  
Table 7-2.  
S108.n=  
Outgoing low-layer compatibility commands  
Function  
S80.n=0  
S80.n=1  
Disable outgoing low-layer compatibility(default)  
Enable outgoing low-layer compatibility  
Example: ATS80.4=0 disables low-layer-compatibility message for analog port 2.  
Control of ISDN Phone Numbers and Subaddresses  
The calling-party number information element identifies the origin of a call, and the called-party  
number information element identifies the destination of a call.  
The calling-party subaddress information element identifies the subaddress associated with the  
origin of a call.  
The called-party subaddress information element identifies the subaddress of the destination of  
a call.  
Each type of outgoing call can be assigned with one number/subaddress pair by using the  
AT&ZOx=s command. The possible values for x are as follows:  
x = I for ISDN data calls  
x = A for the analog adapter 1  
x = B for the analog adapter 2  
Advanced ISDN  
7-3  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
The number-subaddress string s is defined as:  
s = [[Yn][Nn]own-number][/[[Zn]own-subaddress]/]  
Yn specifies the type of number:  
Y0 for unknown (default if Yn is omitted)  
Y1 for international number  
Y2 for national number  
Y3 for network specific number  
Y4 for subscriber number  
Nn is the identifier of the numbering plan:  
N0 for unknown (default if Nn is omitted)  
N1 for ISDN numbering plan (Rec. E.164) (default for Australia if Nn is omitted)  
N3 for data numbering plan (Rec. X.121)  
N4 for telex numbering plan (Rec. F.69)  
N8 for national standard numbering plan  
N9 for private numbering plan  
Zn specifies the subaddress type:  
Z0 for NSAP (Rec. X.213) with AFI=0x50, IA5 characters (default if Zn is omitted)  
Z2 for user specified, IA5 characters  
The command AT&ZOx=// removes the number/subaddress assignment.  
The number and subaddress assigned by AT&ZOx=s, if any, can be used for calling-party number  
and calling-party subaddress information elements, respectively, while dialing.  
The default settings of the phone number and subaddress of all the types of calls are  
UNASSIGNED, meaning the setup message sent by the Model XM128 modem contains neither  
calling-party number nor calling-party subaddress information elements.  
The command AT&ZO? can be used to browse the current settings of the known numbers and  
subaddresses.  
7-4  
Advanced ISDN  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Call Control for 1TR6 (Old German ISDN)  
In order to initiate a 1TR6 ISDN call, two information elements are necessary:  
Service indicator, which determines what kind of bearer services are desired.  
Destination address, which provides necessary information for the telephone company central  
office to direct the call to the remote party.  
Control of Outgoing Service Indicator  
The outgoing service indicator is assigned when you configure the B channel protocols using the  
command ATBnn.  
Because there are a number of combinations of voice or voice-band-data services on the analog  
adapters, users may want to control the outgoing service indicator themselves for some specific  
applications.  
The following information is recommended to configure S104/S107 (service indicator) and S108/  
S111 (additional information octet) according to the terminal types:  
Service indicator  
S107: analog, PHONE 1  
S104: analog, PHONE 2 Addi. S. I.  
S111: analog, PHONE 1  
S108: analog, PHONE 2  
Telephone1 (Fernsprechen)1 (3.1 KHz)  
Modem2 (analog - dienste)3 (Daten Über Modem)  
4 (Btx Über Modem)  
G3 Fax3 (analog - dienste)2 (Fax Gruppe 3)  
Advanced ISDN  
7-5  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
Control of EAZ (ENDGERÄTEAUSWAHLZIFFER)  
EAZ (or terminal selection code) is the last digit of an ISDN phone number in 1TR6. Usually  
EAZ=0 indicates that a global call (any terminal on the S0 interface), which is service-compatible  
with the incoming call, can answer the call.  
Other values of EAZ (1,2,....,9) provide the possibility for assigning multiple ISDN numbers to  
a single ISDN BRI line. A calling user can select, via the public network, one or more distinct  
terminals on a single BRI line.  
With its highly integrated, multifunction features, the Model XM128 modem can be imagined as  
a “black box” containing multiple distinct terminals. Each of these “internal terminals” can be  
assigned one EAZ using the command AT&ZIn=m, where n=0-7 and m= 0-9.  
Command Function  
The following commands are used for assigning EAZs:  
&ZI0=massigns EAZ for X.75  
&ZI1=massigns EAZ for V.110  
&ZI2=massigns EAZ for V.120  
&ZI3=massigns EAZ for PPP, MPPP  
&ZI4=massigns EAZ for ISDN data, protocol auto-detection  
&ZI5=massigns EAZ for PPP, MPPP  
&ZI6=massigns EAZ for PHONE 2  
&ZI7=massigns EAZ for PHONE 1  
The default EAZ of each protocol is as follows:  
&ZI0=1 for data  
&ZI4=2 for data  
&ZI6=3 for the analog adapter, PHONE 2  
&ZI7=4 for the analog adapter, PHONE 1  
T&ZI? for displaying the EAZ numbers assigned by the AT&ZIn=m commands  
7-6  
Advanced ISDN  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
The EAZ (last digit) of the destination address in an incoming setup message is checked with the  
protocol of each EAZ. If there is a match and the service indicated is compatible with this protocol,  
the call be accepted using the protocol.  
Note: The EAZs must be assigned precisely in order to accept calls accordingly.  
The suffix digit to an ISDN phone number in a dial-out command is used as the destination EAZ  
(in the Destination Address W-element) in the setup message sent to the destination. If this suffix  
digit is omitted, the switch assumes the EAZ as 0.  
Each type of outgoing call of the XM128 can be assigned with one origination EAZ by using the  
command AT&ZOx=Origination_EAZ (where x = I for ISDN data calls, A for the analog adapter  
1, and B for the analog adapter 2).  
The command AT&ZOx=// removes the assignment of the origination EAZ.  
The number assigned by AT&ZOx=Origination_EAZ, if any, can be used for the Origination  
Address W-element while dialing. The default settings of origination EAZ of all the types of calls  
are UNASSIGNED, meaning the setup message sent by the Model XM128 modem contains no  
Origination Address W-element.  
The command AT&ZO? can be used to list the current settings of the origination EAZs.  
Answering a Call  
The incoming call first must be identified as either an ISDN data call or a voice call (including the  
voice-band-data call). ISDN data calls are routed to the digital communications portion of the  
Model XM128 modem. Voice calls or voice-band data calls are assigned to the analog adapters.  
Answering a Call for DSS1  
The Multiple Subscriber Number (MSN) supplementary service provides the possibility for  
assigning multiple ISDN numbers to a single ISDN BRI line. Calling users can select, via the  
public network, one or more distinct terminals on a BRI line.  
Advanced ISDN  
7-7  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
In some areas, however, it is very expensive to get additional subscriber numbers. The subaddress,  
which is transferred transparently by the ISDN network between the calling user and the addressed  
user, can be used for the same purpose as the MSN. Because the Model XM128 modem is highly  
integrated and multifunctional, it can be thought of as a black box that contains multiple distinct  
terminals. Each of these internal terminals can be assigned one ISDN number using the  
AT&ZIn=xxxx... command.  
The number assigned by AT&ZIn=xxxx... can be interpreted as either the MSN or the subaddress,  
determined by the bit 5 of S119 as follows:  
S119.5=0 for number treated as the MSN (default)  
S119.5=1 for number treated as the subaddress  
The factory defaults for these numbers are unassigned. If an incoming setup message is offered  
with addressing information (in other words, the appropriate part of the called party number or the  
called party subaddress), this address is compared with the MSN/subaddress numbers assigned by  
the AT&ZIn=xxxx... commands. The call is accepted using the specific protocol if the assigned  
number of this protocol matches the received called party number or called party subaddress.  
Note: Two phone number strings are said to be matched if their least significant n digits  
are identical, where n is the number of digits of the shorter string. Usually one digit is  
enough to distinguish the various protocols.  
Answering a Call for 1TR6  
If an incoming setup message is offered with addressing information (for example, the destination  
address W-element). This address is compared with the EAZ numbers assigned by the AT&ZIn=m  
commands. The call is accepted using the specific protocol if the assigned number of this protocol  
matches with the received address.  
Best-effort Call Answering  
If some numbers have been set using the &ZI command (as can be seen by the AT&ZI? command)  
and they are not matched with the address of the incoming call, the Model XM128 modem, by  
default, ignores the call because it may be intended for other devices that share the same S/T  
interface (S0 bus) with the modem.  
7-8  
Advanced ISDN  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
If you want the Model XM128 modem to answer inbound calls as often as possible, you can set the  
best-effort call answering bit as follows:  
S119.3=0 for Answering call only when number matched (by default)  
S119.3=1 for best effort call answering  
Ambiguity Resolution Switch for Voice Calls  
For a voice or voice-band data call, if the &ZI number assignment can tell which of the analog  
adapters is being addressed, then the call is delivered to the proper destination. Sometimes,  
however, ambiguity of address matching may exist. This ambiguity may happen if the &ZI  
numbers of the various protocols are either unassigned or not matched or the address information  
is absent in the incoming setup message. In this case, users may wish to set the priority of  
answering a call by the analog adapter PHONE 1 or the analog adapter PHONE 2.  
The AT&Ln command sets the address ambiguity resolution flag:  
AT&L0  
The analog adapter 1 has the higher priority to answer a voice or voice-band-data call. If the  
analog adapter 1 is busy, the call is routed to the analog adapter PHONE 2.  
AT&L1  
The analog adapter 2 has the higher priority to answer a voice or voice-band-data call. If the  
analog adapter 2 is busy, the call is routed to the analog adapter PHONE 1.  
Multi-Auto-Answering of Data Calls  
For an ISDN data call, if the Model XM128 modem can exclusively determine the protocol to be  
used by means of the information conveyed by the setup message (for DSS1, this information  
includes the bearer capability, low-layer compatibility, or high-layer compatibility information  
elements; for 1TR6, it includes the service indicator as well as the Additional Octet of Service  
Indicator), then the indicated protocol is used. Otherwise, the Multi-Auto Answering process is  
invoked. The Model XM128 modem can monitor the B channel signal sent by the calling site.  
The data call can be identified by the Model XM128 modem as X.75, V.110, V.120, or PPP  
Async-to-Sync conversion and MPPP.  
Advanced ISDN  
7-9  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
Data Call Indication  
Data calls are accepted by the Model XM128 modem in the same way as with any terminal  
adapter. When alerting, the Model XM128 modem sends the first Ring message to the DTE with a  
format as follows:  
RING <CR><LF>  
[FM:[[Prefix]Calling-Party-Number][/Subaddress/]]  
[TO:[Called-Party-Number][/Subaddress/]] <CR><LF>  
RING <CR><LF>  
RING <CR><LF>  
The display of address information between the first Ring and the second Ring is disabled by  
setting ATS84.4=1. The term Prefix is a predefined number string is added in front of the  
calling-party number before indicating it to the DTE. Adding Prefix is useful for some automatic  
dial-back-up systems. The number string is assigned as follows:  
ATCI<Prefix>  
When and only when the type of number denotes an international number, this "Prefix" is  
added to the calling-party number before indicating it to the DTE.  
ATCI<>  
This command disables the international number prefix-adding function. (Default)  
ATCN<Prefix>  
When and only when the type of number denotes a national number, this "Prefix" is added  
to the calling-party number before indicating it to the DTE.  
ATCN<>  
This command disables the national number prefix-adding function. (Default)  
Note: The angle brackets (<) and (>) are part of this command.  
Disable Inbound Call Connection  
In some cases, the user may require that the Model XM128 modem not answer any incoming calls.  
This response is accomplished by setting the bit 0 of S-register S118 as follows:  
S118.0=0 to enable answering a call (by default)  
S118.0=1 to disable answering any call  
7-10  
Advanced ISDN  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
Point-to-Point Configuration  
In some areas, the Direct-Dial-In (DDI) number is less expensive than the MSN; therefore, you  
might want to subscribe to point-to-point ISDN to employ the DDI function. In this case, only one  
modem can be connected to the ISDN line and the TEI (Terminal Equipment Identifier) is always  
zero. The TEI is established by setting the bit 1 of S-register S119 as follows:  
S119.1 = 0 to disable point-to-point DDI function (default)  
S119.1 = 1 to enable point-to-point DDI function  
Placing a Call  
To initiate a call, configure the Model XM128 modem according to the bearer service (or protocol)  
that you want to use.  
ATBnn is used for ISDN data calls.  
Placing a Call for DSS1  
The ATDx command ATDx[Yn][Nn]called_party_number[/[Zn]called-party-subaddress/] is used  
for dialing.  
Where x = I (for ISDN data calls), A (for the analog adapter 1), or B (for the analog adapter 2).  
Yn specifies the type of number:  
Y0 for unknown (default if Yn is omitted)  
Y1 for international number  
Y2 for national number  
Y3 for network specific number  
Y4 for subscriber number  
Advanced ISDN  
7-11  
 
           
Reference Guide for the Model XM128 ISDN Digital Modem  
Nn is the identifier of the numbering plan for the ATDx command:  
N0 for unknown (default if Nn is omitted)  
N1 for ISDN numbering plan (Rec. E.164)  
N3 for data numbering plan (Rec. X.121)  
N4 for telex numbering plan (Rec. F.69)  
N8 for national standard numbering plan  
N9 for private numbering plan  
Zn specifies the type of the subaddress:  
Z0 for NSAP (Rec. X.213) with AFI=0x50, IA5 characters (default if Zn is omitted)  
Z2 for user specified, IA5 characters  
The called-party number or an appropriate part of it is sent to the addressed entity. The called-party  
subaddress is transferred transparently by the ISDN network to the destination.  
Use ATDL to redial the last dialed telephone number (and/or subaddress).  
Placing a Call for 1TR6  
The ATDx[Yn][Nn]destination_address command is used for dialing as follows:  
x = I (ISDN data), A (the analog adapter 1), or B (the analog adapter 2)  
Yn specifies the type of address:  
Y0 for unknown (default if Yn is omitted)  
Y1 for international number  
Y2 for national number  
Nn is the identifier of numbering/addressing plan:  
N0 for unknown (default if Nn is omitted)  
N1 for ISDN numbering plan (Rec. E.164)  
The destination address is the ISDN phone number of the called party. The last digit of this number  
is the EAZ. Use ATDL to redial the last dialed ISDN phone number.  
7-12  
Advanced ISDN  
 
   
Reference Guide for the Model XM128 ISDN Digital Modem  
User-To-User Information  
The Model XM128 modem supports user-to-user information exchange via the D channel. To  
transmit a message, use the ATT4<message.....> command. The angle brackets (< >) are part of  
this command. The message is included in a user-to-user information element, which is sent with  
the first valid message that follows.  
If the ATT4<message.....> command is issued before dialing, the user-to-user information element  
is sent in the setup message. Whether the information element can be sent to the called party or not  
is switch dependent. If the switch supports this information element, the called party can see the  
message before the call is answered.  
During a call connection session, the D channel is still used to exchange user-to-user information.  
For the single stream configuration, both sides must be in Escaped state because only then can they  
send the AT commands and view the responses.  
The user-to-user information element is a supplementary service that has to be invoked on a  
per-call basis.  
Advanced ISDN  
7-13  
 
   
 
Chapter 8  
Analog Call Handling  
This chapter outlines the steps required to place and answer analog calls through the ISDN line for  
your Model XM128 ISDN Digital Modem.  
The analog adapters enable you to connect analog devices (for example, telephone, fax, or modem)  
to an ISDN basic rate line. Any conventional analog telephony equipment that supports desktop  
management task force (DTMF) tone/pulse dialing can be plugged into either of the two RJ-11  
connectors (labeled PHONE 1 and PHONE 2) on the back of the Model XM128 modem.  
The analog adapters use RJ-11 phone jacks. The pin assignment of the connectors and plugs are  
shown in Appendix E, “Connector Pin Assignments.”  
Note: German NETGEAR customers: The inner two pins of the RJ-11 are used for the  
Tip and Ring (or a and b signals in Germany, the two signals that connect to a telephone  
set). This is the standard pin assignment, but some BZT-approved telephones use the  
outer two pins for a and b. If this is the case, use the attached TAE adapter, which has a  
unique interface definition, or use an RJ-11 cable that connects the inner pins on one end  
and the outer pins on the other end.  
Analog Call Handling  
8-1  
 
   
Reference Guide for the Model XM128 ISDN Digital Modem  
AT Commands for Analog Calls  
Table 8-1 lists some of the most frequently used AT commands.  
Table 8-1.  
Frequently used AT commands  
Description of command  
AT Command  
ATDAs  
Automatically dials out for device connected to PHONE 1.  
The number string to dial is represented by the letter s.  
ATDBs  
AT&V6  
AT&V7  
Automatically dials out for device connected to PHONE 2.  
View current setting of analog adapter, PHONE 1.  
View current setting of analog adapter, PHONE 2.  
Assign analog calls to PHONE 1 if the line is not in use.  
AT&L0  
orATS84.5=0  
AT&L1  
Assign analog calls to PHONE 2 if the line is not in use.  
orATS84.5=1  
AT&ZIn=s  
MSN setting, assign called phone number, s, to be answered by n port  
(where n=6 for PHONE 1 and n=7 for PHONE 2).  
AT&ZI6=s  
AT&ZI7=s  
ATS56=n  
Assign the called phone number for analog adapter, PHONE 1.  
Assign the called phone number for analog adapter, PHONE 2.  
Flash timer, in 100 ms unit, to set maximum duration of on/off hook  
transition to be recognized as flash.  
Table 8-2 lists the AT commands that are specific to European switches.  
Table 8-2.  
Frequently used AT commands (European switches)  
AT Command  
ATS89.6=0  
ATS89.6=1  
ATS89.5=0  
ATS89.5=1  
Description of command  
To disable the metering pulse for analog adapter, PHONE 1  
To enable the metering pulse for analog adapter, PHONE 1  
To disable the metering pulse for analog adapter, PHONE 2  
To enable the metering pulse for analog adapter, PHONE 2  
8-2  
Analog Call Handling  
 
           
Reference Guide for the Model XM128 ISDN Digital Modem  
Making and Receiving Analog Calls  
This section explains the role of analog adapters in placing outgoing analog calls and receiving  
incoming analog calls.  
Placing a Call from the Analog Adapter  
Making a call from the analog adapter is as easy as picking up the telephone connected to the  
analog port and dialing. With a terminal program, you can also use the Model XM128 modem  
to dial the number for you.  
To place a call from the analog adapter, follow these steps:  
1. Type ATDB714-693-0808 (dial the number).  
You should see this message:  
CONNECT (Dialing is complete)  
2. Pick up the phone handset and wait for the remote device to answer.  
3. Use ATDAs (ATDBs) to place a call for the analog adapter 1 (analog adapter 2).  
When the hook sensor of the analog adapter detects that the handset on the telephone device is  
picked up (off hook), it sends a setup message to the ISDN central exchange to request a  
connection. One B channel, if available, is assigned to this connection, and the exchange waits  
for the dialed number to route the call. At the same time, a dial tone is presented to the adapter  
port to prompt the user to dial. Both tone and pulse dialing are accepted.  
A busy tone is heard on the handset if:  
The B channel is unavailable.  
The dialed number is undeliverable.  
The called party is busy.  
This busy tone indicates the failure of the attempt to connect. To place another call, hang up  
the phone; then pick it up again. If the called party is alerted, a ring-back tone is heard.  
Analog Call Handling  
8-3  
 
   
Reference Guide for the Model XM128 ISDN Digital Modem  
Accepting an Incoming Call  
Incoming ISDN calls are directed to one of the analog ports (PHONE 1 or PHONE 2) if:  
A voice call is sent to one of the two analog adapters automatically when it is received. As the  
manufacturer default, the call is sent to the analog adapter, PHONE 1, first then PHONE 2 if  
PHONE 1 is busy.  
The MSN is set (AT&ZIn=s, as shown in Table 6-1 to specify the phone number (s) the remote  
user dialed to be sent to specific analog adapter, n.  
The MSN setting for the phone number in the incoming setup message is acceptable to both  
the analog adapters, and the ambiguity resolution bit is set to 0 or 1.  
8-4  
Analog Call Handling  
 
 
Chapter 9  
Modem Upgrade  
This chapter describes how to upgrade flash electrically erasable programmable read-only memory  
(EEPROM) firmware on your Model XM128 ISDN Digital Modem.  
Upgrading with Flash EPROM  
Your Model XM128 modem employs a flash EEPROM that lets you conveniently download  
updated firmware and program the modem with new features and enhanced functions. If you are  
using Windows 95 or Windows NT, use the NETGEAR Internet Configuration Manager to  
upgrade the firmware. For other operating systems, use a terminal program that supports the  
X-modem Protocol.  
Obtain the new firmware from the NETGEAR bulletin board system (BBS), WWW, or FTP site.  
Refer to Customer Support on page -iii. The firmware is distributed in the ONETd.vvv file, where  
the extension vvv denotes the version of this firmware. Table 9-1 lists the definitions for the d  
modifier in the file name.  
Table 9-1.  
Modifier  
Definitions for the d modifier  
Definition  
G
E
German national ISDN (1TR6)  
European ISDN (DSS1)  
European ISDN is also used in most other countries including Asian  
countries.  
A
American ISDN (AT&T 5ESS, Northern Telecom DMS-100, or National  
ISDN-1)  
The active D channel protocol can be chosen by an AT command.  
Note: The American firmware version supports both the S/T interface and U interface  
models. During power-on test, it checks the hardware configuration and follows the  
initialization procedures of the specific interface.  
Modem Upgrade  
9-1  
 
         
Reference Guide for the Model XM128 ISDN Digital Modem  
Upgrade Instructions  
To upgrade your Model XM128 modem, turn the modem on and follow these steps:  
1. Start any communications program that supports the X-modem Protocol.  
2. Enter the command ATUPX.  
Your Model XM128 modem responds:  
You have chosen Xmodem (128 octets of data with checksum) protocol to  
update your ISDN modem. Data in Flash ROM will be erased !!!  
Are you sure (Y/N) ?  
3. Press Y.  
The following message appears:  
Start programming, please upload.  
4. Use the X-modem Protocol to upload the file ONETd.vvv to your Model XM128 modem.  
This step updates the flash EEPROM of the modem with the new firmware. When  
installation is complete, the Model XM128 modem restarts automatically.  
Kernel Mode  
In the unlikely event that your Model XM128 modem fails to respond to AT commands after  
upgrading the EEPROM, turn on power to the modem. The reset prompts the modem to check the  
integrity of the codes in the flash EEPROM. If proper valid firmware cannot be verified, the  
modem initiates kernel mode. When the Model XM128 modem is in kernel mode, you can issue  
limited AT commands. Start from step 2 of the upgrade instructions on this page.  
9-2  
Modem Upgrade  
 
   
Chapter 10  
Troubleshooting  
This chapter provides quick easy-reference troubleshooting tables for the Model XM128 ISDN  
Digital Modem. For troubleshooting purposes, the Model XM128 modem performs its own  
diagnostic tests, which can provide information about each of its functions.  
The Model XM128 modem provides several diagnostic capabilities:  
Power-on self-test  
Local digital loopback tests  
Diagnostic command  
Modem reset  
Power-on Self-test  
At each power-up sequence or upon a reset command from the panel, the Model XM128 modem  
tests the ROM code checksum, system RAM memory, EEPROM, digital and analog circuit  
calibrations, and analog circuit calibrations.  
Table 10-1 summarizes the power-on self-test of the Model XM128 modem.  
Table 10-1.  
Power-on self-test  
Test Sequence  
LED LNK  
LED B1  
LED B2  
LED AA  
Test Description  
1
2
3
4
On  
Off  
Off  
Off  
Off  
On  
Off  
Off  
Off  
Off  
On  
Off  
Off  
Off  
Off  
On  
Memory test  
ISDN chip interface test  
ISDN chip functional test  
HDLC functional test  
Troubleshooting  
10-1  
 
           
Reference Guide for the Model XM128 ISDN Digital Modem  
Note: The LED lights up during the test and blinks if the test fails.  
The LNK LED light s up for a half second to indicate the success of the power-on self-test. Then  
the LNK LED becomes the normal physical layer (layer 1) active indicator.  
Loopback Tests  
The Model XM128 modem performs several loopback tests as part of its diagnostic capabilities.  
ISDN Loopback test (AT&T9)  
The AT&T9 command invokes an ISDN loopback test connection. The loopback point is in the  
S/T interface chip (Siemens 2086 chip) or the U interface chip (Siemens 2091 chip) just behind the  
line transformers. It checks almost every part of the Model XM128 modem and RS-232 cable  
except the passive front end of the ISDN S/T or U interface.  
During this test, data from the terminal or computer is sent through the DTE interface to the  
transmitter of the Model XM128 modem. Data is then packetized to the proper frame format  
according to the B channel protocol selected. Finally, the data is looped back to the receiver,  
depacketized, and sent through the DTE interface back to the terminal or computer screen. You can  
tell if anything is wrong by looking at the screen. The screen shows the data you sent to the  
Model XM128 modem.  
Loopback with Self-test (AT&T10)  
The AT&T10 command invokes an ISDN loopback connection with self-test. The data is  
generated by the Model XM128 modem and goes through the same path as the above loopback test  
does. The data pattern is printable ASCII characters, so you can see the result on the screen. The  
looped back data is compared with the transmitted data. Should an error occur, the LNK LED  
starts to flash. Any character sent through the DTE interface to the Model XM128 modem  
discontinues the test.  
10-2  
Troubleshooting  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
B1/B2 Loopback with Self-test  
An AT and T11 command is designed for testing the readiness of your ISDN line that uses one  
B channel (B1) to place a call to itself and uses the other B channel (B2) to receive the call. This  
test is a modem loopback test.  
To make your test call, follow these steps:  
1. Enter the command AT&ZOI=your_isdn_number.  
Your Model XM128 modem responds with:  
OK  
2. Enter the command AT&T11.  
Your Model XM128 modem responds with:  
OK  
Dial your_isdn_number  
Loop from B1 to B2 through the switch established!  
Sending and receiving data.....  
B1/B2 loopback test successed.  
Disconnecting.....  
NO CARRIER  
The modem loopback test is complete.  
The Diagnostic Command  
The ATCG command is used to test and isolate fault if there are any hardware problems in the  
Model XM128 modem. Some of the tests are interactive operations. Follow the instructions  
prompted on the screen to carry out the tests. If the modem is in the normal condition, the test  
results printed on the screen are as follows:  
System address & data bus test .......................OK  
Layer 1 hardware test ............................... OK  
Layer 2 hardware test ............................... OK  
Layer 1 activation test.............................. OK  
First B channel hardware test ....................... OK  
Second B channel hardware test....................... OK  
Listen to the Ring and then pick up phone set #1..... !!  
Off-hook action is detected, (Hook Interrupt) ....... OK  
Listen to the dial tone and then dial 1234567890*# in sequence.!!  
1234567890*#  
Troubleshooting  
10-3  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
Dialed digits detected, please hang-up the handset….!!  
On-hook action is detected, (Hook Interrupt)........ OK  
Listen to the RING and then pick up phone set #2 ....!!  
Off-hook action is detected, (Hook Interrupt) ....... OK  
Listen to the dial tone and then dial 1234567890*# in quence.!!  
1234567890*#  
Dialed digits detected, please hang-up the handset ..!!  
On-hook action is detected, (Hook Interrupt) ........ OK  
Listen to the prompt signal of the Internal Speaker and then press the button  
switch.......!!  
Button switch is pushed (Button Interrupt) .......... OK  
Modem Reset  
If you have modified the setting of the Model XM128 modem and cannot get it back because the  
unit is locking up, or you just want to reset it back to the factory default state, the following reset  
procedure helps you to reset the modem back to the factory default state.  
To reset the Model XM128 modem back to the factory default state, follow these steps:  
1. Hold the DATA/VOICE button down while turning the unit on.  
Continue holding the switch down for 3 seconds after the power switch is turned on.  
2. Release the switch.  
The Model XM128 modem resets itself back to the factory setting and runs a continuous  
loopback self-test. If the modem is connected to a terminal, printable characters show on the  
terminal screen.  
3. Turn power to the modem off and then back on again.  
Using The Embedded Protocol Analyzer  
This section describes how to set up the embedded protocol analyzer (EPA) and capture and  
analyze the protocol data.  
10-4  
Troubleshooting  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
Setting up the Embedded EPA  
The EPA records and analyzes various protocols on the B channel, D channel and DTE-DCE  
interface. The results are displayed with ANSI color. This professional tool is designed for  
hobbyists as well as users with technical backgrounds. The EPA enables you to examine messages  
exchanged between your Model XM128 modem and the Central Exchange office when making an  
ISDN call. You can review the packets sent or received through the B channel (for X.75 or V.120  
protocols) to or from the remote site. You can also check the AT commands issued from an  
application software program. This helps you understand their causal relationship with other  
events.  
In addition to its tutorial purpose, the EPA is very useful for diagnostics. If you have compatibility  
problems with your Central Exchange or with the TA at the remote site, the EPA is your first aid  
resource. According to the analysis of the EPA, you might decide to fix the problem yourself  
( modify the configuration and try again) or log the analyzed results as a file (a very  
comprehensive bug report), and then send it to NETGEAR Technical Support.  
Capturing the Protocol Data  
The data captured by the EPA is classified into three categories:  
B channel user data protocols  
D channel signaling protocols  
DTE-DCE protocols  
The D channel signaling protocols include layer 2 and layer 3 call control protocols. Frames and  
messages exchanged through the D channel are all recorded for further analysis. These data  
messages are essential to understanding interactive operations between an ISDN TA and the ISDN  
network. They contain the compatibility information for the Model XM128 modem and your  
Central Exchange.  
The B channel user data protocols include X.75 and V.120 protocols. Only the layer 2 header  
(addresses and control bytes) and layer 3 header are captured. Since the X.75 protocol can be used  
with various layer 3 protocols (T.70, T.90, and ISO8208 protocols), only the first 8 octets of the  
information field are recorded as the layer 3 header, and are displayed in raw data form. The  
analysis of the protocol data is carried out by NEGEAR Technical Support.  
Troubleshooting  
10-5  
 
           
Reference Guide for the Model XM128 ISDN Digital Modem  
The DTE-DCE protocols (at the R reference point according to the ISDN nomenclature) include  
the AT commands/responses as well as the CAPI internal interface. The CAPI internal interface is  
used with NETGEAR CAPI driver. The NETGEAR CAPI driver communicates with the  
Model XM128 modem through this internal interface. It is not recommended that users get  
involved in this internal interface. The AT commands/responses, on the other hand, are in a  
standard user interface. An analysis of these commands and responses might prove very  
informative. All messages captured by the EPA are tagged with a time stamp according to a free  
running timer that starts at the beginning of data capture. The resolution of this timing information  
is in 0.01 second.  
The commands listed in Table 10-2 determine the kind of protocol data to be captured by the EPA.  
Table 10-2.  
EPA Commands  
Description  
AT Command  
ATCDn n = 0 Disables the capture of D channel protocols  
n = 1 Enables the capture of D channel protocols (default)  
ATCBn n = 0 Disables the capture of B channel protocols (default)  
n = 1 Enables the capture of B channel protocols  
ATCCn n = 0 Disables the capture of DTE-DCE interface protocols (default)  
n = 1 Enables the capture of DTE-DCE interface protocols  
The EPA starts to capture data when the command ATCT is issued. This capturing process  
continues until the command ATC$ is issued. The EPA maintains 8 Kbytes RAM as a ring buffer.  
In case the buffer is full, the earliest data captured is overwritten by the latest data.  
Analyzing the Captured Data  
To view the analyzed result, use the command ATC$. The relevant AT commands are summarized  
in Table 10-3.  
Table 10-3.  
Commands for analyzing captured data  
Description  
AT Command  
ATCT  
Clears buffer and starts the embedded protocol analyzer. Captures data  
immediately and starts the timer.  
ATC$  
10-6  
Invokes the interpretation function of the embedded protocol analyzer and  
displays the results on the DTE screen.  
Troubleshooting  
 
               
Reference Guide for the Model XM128 ISDN Digital Modem  
The analyzed results can be viewed as if contained in a full screen editor. Several number keys are  
used to control the display. For PC users, it is convenient to use the keys on the numeric keypad  
(make sure that Num-Lock is on.).  
The functions of the control keys are listed in Table 10-4. Any other key pops up the control menu.  
Table 10-4.  
Control key functions  
Key  
Function Description  
1
End  
Display to the end of buffer  
2
Cursor down  
Page down  
Home  
Scroll one line up  
3
Display the next page  
Display the first page  
7
8
Cursor up  
Page up  
Quit  
Scroll one line down  
9
Display the previous page  
Quit embedded protocol analyzer  
Q, q  
Troubleshooting  
10-7  
 
     
 
 
Appendix A  
Technical Specifications  
This appendix provides the technical specifications for the Model XM128 ISDN Digital Modem.  
General Specifications  
Network Protocols and Standards Compatibility  
WAN Protocols:  
ISDN Standards:  
Multilink PPP, BACP, PPP V.120, V.110, X.75  
National ISDN-1 (North America)  
AT&T 5ESS Custom (North America)  
1TR6 (Europe)  
Nortel DMS-100 (North America)  
EURO ISDN ETSI/NET-3/CTR3 (Europe)  
NTT INS-Net64 (Japan)  
Compatibility:  
AT Command Set with ISDN extensions  
DTR Dialing Supplementary Services  
Calling Line Identification  
Security  
PAP, CHAP, Caller ID, Callback, Call blocking  
Technical Specifications  
A-1  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
Data Compression  
Power Adapter  
Hi/fn LZS (Stac) Compression with CCP  
V.42bis  
16 V, 1A (22W max.)  
UL/CSA (North America)  
CE/TUV (Europe)  
TMark (Japan)  
Physical Specifications  
Dimensions:  
190 x 122 x 31 mm  
7.5 x 4.8 x 1.2 in.  
0.7 kg  
Weight:  
1.6 lb  
Environmental Specifications  
Operating temperature:  
Operating humidity:  
0° C to 40° C  
90% max. relative humidity, noncondensing  
Electromagnetic Emissions  
CE Mark  
FCC Part 15 Class B  
EN 55 022 (CISPR 22), Class A  
VCCI Class 2  
A-2  
Technical Specifications  
 
Appendix B  
Security Functions  
This appendix describes the security functions of the Model XM128 ISDN Digital Modem. The  
modem provides two types of security functions that may be enabled to prevent unauthorized  
connections.  
Security Types and Levels  
The Model XM128 modem provides the following types of security:  
Type 1 security is used when the remote modem is a NETGEAR modem.  
Type 2 security is used when the remote modem is a non-NETGEAR device.  
With a Type 1 connection, the dial-in (remote) modem sends in its supervisor password for  
matching with the prestored password list of the local modem. With a Type 2 connection, the  
remote terminal is prompted to enter the password at the initial connection. The local  
Model XM128 modem matches the entered password with the prestored password list.  
Security Functions  
B-1  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
The two types of security are summarized in Table B-1.  
Table B-1.  
Types of security  
Type 1 Security  
Type 2 Security  
Remote (Calling) Site NETGEAR ISDN device only  
Can be modem of any brand  
Interactive  
Password Check  
Protocols Supported  
AT Commands  
Automatic  
X.75, V.120  
Any data protocol  
*G1 for Level 1 security  
*G2 for Level 2 security  
*G3 for Level 1 security  
*G4 for Level 2 security  
*G5 for Level 3 security  
Level 1 Security  
This security level performs only password checking. With Level 1 security, the local modem  
maintains the connection if the password is matched. Otherwise, the line is disconnected.  
Level 2 Security  
Level 2 security provides extra calling party number (CPN) checking and callback. The callback  
number is prestored in the password table. If the password has been matched (in a maximum of  
three tries over a 40-second time period) with its prestored password list, the local modem checks  
the calling party number (or origination address for 1TR6) against the prestored number  
corresponding to the password. If they are matched, the local modem chooses either to keep the  
connection or to disconnect; then it calls back according to the following settings of bit 6 of S119:  
S119.6=0  
This setting prompts the modem to connect and then to call back.  
S119.6=1  
This setting prompts the modem to keep the connection.  
If the CPN does not match what is stored in the table, the local modem disconnects the call. If CPN  
is unavailable in the setup message, the local modem disconnects the call and calls back using the  
prestored number corresponding to the dial-in password.  
B-2  
Security Functions  
 
           
Reference Guide for the Model XM128 ISDN Digital Modem  
Level 3 Security  
After the password is matched, the local modem prompts the remote user to enter a callback  
number.  
The three levels of security are summarized in Table B-2.  
Table B-2.  
Levels of security  
Level 1  
Level 2  
Level 3  
Password Check  
Yes  
N/A  
Yes  
Yes  
CPN Check OK  
and S119.6=0  
Call back  
Prompts the remote  
user to enter callback  
number for calling  
back  
CPN Check OK  
and S119.6=1  
N/A  
Keep the  
connection  
CPN unmatched  
CPN not Available  
N/A  
N/A  
Disconnect  
Call back using the  
corresponding  
prestored number  
AT Commands  
*G1 for Type 1  
*G3 for Type 2  
*G2 for Type 1  
*G4 for Type 2  
*G5 for Type 2  
Setting and Modifying Passwords  
The AT*Hn command (where n represents the index to the entry) can define 40 user passwords.  
Numbers between 0 and 39 are accepted.  
The corresponding 40 callback numbers are defined by the AT&Zn=xxx command, where n  
represents the index to the entry and xxx represents the assigned callback phone number. Any  
character (ASCII 0-127) can be used in the password table. The maximum password length is eight  
characters for each entry.  
The security functions are accessible only through AT commands in terminal mode. A supervisory  
password is required for adding or modifying the entries. The default supervisor password is  
NETGEAR when the Model XM128 modem is shipped from the factory. This supervisory  
password is sent to the remote user if Type 1 security is set at the remote end.  
To modify the supervisor password, use the command AT*HS.  
Security Functions  
B-3  
 
           
Reference Guide for the Model XM128 ISDN Digital Modem  
You are asked to enter the original password, to enter a new password, and then to reenter the new  
password for verification. For example, you are prompted with the following:  
Password:  
Enter the current supervisory password at this prompt. You are then prompted for a new password.  
Password:  
Enter the new supervisory password at this prompt. You are then prompted to verify the new  
password.  
Verify:  
Enter the new supervisory password again at this prompt. You should receive the following  
response:  
OK  
The supervisory password is now modified.  
Use the command AT*Hn to modify the nth user password. You are prompted to enter the  
supervisory password first; then the user’s password for this entry is requested and verified. The  
command AT*V lists both the 40 user passwords and the supervisor password on the screen for  
viewing.  
Nonpassword Auto Callback Function  
In addition to the standard modem-like security functions described in the previous section, the  
Model XM128 modem provides another simpler callback function. The calling party number  
(origination address) is checked against the five prestored callback numbers before the B channel  
is connected. If the CPN is matched with any one of the numbers, the incoming call is rejected  
(without connection and without any charge) and the Model XM128 modem automatically calls  
back using the matched phone number. Table B-3 lists the auto callback commands.  
Table B-3.  
Command  
Auto callback commands  
Description  
AT*GC0  
AT*GC1  
This command disables the auto callback function (default).  
This command enables the auto callback function.  
AT*HCn=xxxx, - n=0,1,..,4 This command sets the prestored numbers.  
AT*VC  
This command lists all the prestored numbers.  
B-4  
Security Functions  
 
     
Appendix C  
AT Command Set Reference  
This appendix provides information for using AT commands for the Model XM128 ISDN Digital  
Modem.  
Operation Mode of the DTE Interface  
The operation mode for the DTE interface is Simplex mode. This mode is used for conventional  
AT command operation.  
Simplex Mode  
In simplex mode, the Model XM128 modem is used just like an ordinary modem. The DTE  
interface is either in the command state or in the data state. Only one data connection session is  
possible at any time.  
To perform various functions of the Model XM128 modem, a number of different AT commands  
can be used. The simplex mode is designed for AT command users. The guides and descriptions  
throughout the rest of this manual, if not otherwise specified, are applicable to this mode. The  
power-on default of the DTE interface is in simplex mode as well.  
AT Command Set Reference  
C-1  
 
         
Reference Guide for the Model XM128 ISDN Digital Modem  
AT Command Descriptions  
The AT command is a command in asynchronous data format issued by the computer to the Model  
XM128 modem through the asynchronous computer-modem interface. AT commands control the  
behavior and actions of the modem.  
To send an AT command from a computer to the Model XM128 modem, the following rules apply:  
You must be running a communication software.  
The modem must be in the command state.  
The commands A/, A>, and +++ are exceptions. These commands are not preceded by AT or  
followed by any more characters.  
The AT command prefix can be typed in either uppercase letters (AT) or lowercase letters (at).  
Do not combine uppercase and lowercase letters in the prefix.  
Table C-1, Table C-2, Table C-3, and Table C-4 list the AT commands supported by the Model  
XM128 modem. An asterisk (*) following a command option or value indicates that it is a default  
setting when the Model XM128 modem is shipped. Table C-1 lists the basic AT command set.  
Table C-1.  
Command  
Basic AT command set  
Options Function and description  
A/  
Re-executes the last command once.  
A>  
Reexecutes the last command once or repeats the last call up to 9 times. You  
can abort this command by pressing down on any key on the keyboard or front  
panel. This command is also aborted when a successful connection with a  
remote modem is made. See also S-register S8. For a description of Basic  
S-registers, refer to Table D-3 on page D-4 in Appendix D, “Status Registers  
and Result Codes."  
Pressing any  
key  
Terminates the current connection attempt when any key is pressed.  
+++  
A
Exits the data transfer state and begins the command entry state.  
Goes online in answer mode. See also S-registers 39.2 and S43.6. For a  
description of Extended S-registers, refer to Table D-4 on page D-5 in  
Appendix D, “Status Registers and Result Codes."  
C-2  
AT Command Set Reference  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
Basic AT command set (continued)  
Table C-1.  
Command  
Options  
Function and description  
Bnn  
Select ISDN Teleservice. B must be followed by two digits.  
See also S-registers 82 and 102. For a description of Extended S-registers,  
refer to Table D-4 on page D-5 in Appendix D, “Status Registers and Result  
Codes."  
B00  
B01  
B04  
B10  
X.75 Transparent  
X.75 T.70  
BTX (Data X-J)  
V.110 user rate follows DTE speed (async) or V.110 user rate determined by  
in-band negotiation (sync)  
B13  
V.110 user rate = 2400 bps. See also S-register 117. For a description of  
Extended S-registers, refer to Table D-4 on page D-5 in Appendix D, “Status  
Registers and Result Codes."  
B14  
B15  
B16  
B17  
B18  
B19  
B20  
B40  
B41  
V.110 user rate = 4800 bps  
V.110 user rate = 9600 bps  
V.110 user rate = 14400 bps  
V.110 user rate = 19200 bps  
V.110 user rate = 384000 bps (sync only)  
V.110 user rate = 576000 bps (sync only)  
V.120  
PPP async to sync conversion  
SLIP async to sync conversion  
CEn  
Call bumping for MPPP and CCB. See also S-register 85.0. For a description  
of Extended S-registers, refer to Table D-4 on page D-5 in Appendix D, “Status  
Registers and Result Codes."  
CE0  
CE1  
Disable call bumping function.  
Enable call bumping function.  
CH?  
Display the accumulated charging unit of the last call.  
CI<prefix>  
Prefix number string to be added to the Calling-party-number before indicating  
to the DTE when the type of number denotes international.  
CLn  
n=0-2048  
Maximum size of user data in a packet (number of octets).  
Inquire current setting of ATCLn.  
CL?  
CN<prefix>  
Prefix number string to be added to the calling party number before indicating  
to the DTE when the type of number denotes national.  
AT Command Set Reference  
C-3  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Table C-1.  
Basic AT command set (continued)  
Command  
Options  
Function and description  
CPn  
Loopback 4 control  
CP0  
CP1  
Disable Loopback 4  
Enable Loopback 4  
CRn  
CSn  
Ds  
n=0-3  
0 *  
n=0-3  
0 *  
Suspends a call; n is the call identifier (Europe).  
Dial s numbers and options that follow. See also S-register 38.0 and 35.4. For  
a description of Extended S-registers, refer to Table D-4 on page D-5 in  
Appendix D, “Status Registers and Result Codes."  
The s options are listed as follows:  
,
Pause for a time specified in S6. Remaining digits are dialed as in-band  
DTMF.  
+
W
Prefix for the second number string, to be used in making bundling or MPPP  
calls.  
Wait for second dial tone. Remaining digits are dialed as in-band DTMF (ISDN  
numbering options).  
Y0  
Y1  
Y2  
Y3  
Y4  
Y6  
Z0  
Z2  
N0  
N1  
N3  
N8  
N9  
/
Unknown type of number  
International number  
National number  
Network-specific number  
Subscriber number  
Abbreviated number  
Type of subaddress, NSAP with AFI=$50, IA5 characters  
Type of subaddress, user specified, IA5 characters  
Unknown numbering plan  
ISDN/Telephony numbering plan (CCITT E.164/E.163)  
Data numbering plan (CCITT X.121)  
National standard numbering plan  
Private numbering plan  
Called party subaddress delimiters  
Format of “s” [[Yn][Nn]called_party_number][[W][,]]inband_dtmf_number  
or  
[[Yn][Nn]called_party_Number][/[Zn]called_party_subaddress/]  
C-4  
AT Command Set Reference  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Basic AT command set (continued)  
Table C-1.  
Command  
Options  
Function and description  
DAs  
DBs  
DIs  
Dial s (number and options) that follows for the analog adapter, PHONE 1.  
Dial s (number and options) that follows for the analog adapter, PHONE 2.  
Dial s (number and options) that follows for ISDN data call.  
Repeat last ATD command.  
DL  
DNn=m  
User enters DNs (USA switches)  
DN0=  
DN1=  
n=0-39  
First phone number (m=seven-digit phone number for North American  
switches).  
Second phone number (m=seven-digit phone number for North American  
switches).  
DSn  
En  
Dial number stored in nonvolatile RAM at location n. Use a plus sign (+) to dial  
two consecutive numbers for bundling or MPPP calls. See also S-register  
44.3. For a description of Extended S-registers, refer to Table D-4 on page D-5  
in Appendix D, “Status Registers and Result Codes."  
Command mode local echo of keyboard commands. See also S-register 23.0.  
For a description of Extended S-registers, refer to Table D-4 on page D-5 in  
Appendix D, “Status Registers and Result Codes."  
E0  
Echo off  
E1  
*
*
Echo on  
Hn  
In  
On/off hook control  
H0  
H3  
H4  
Hang up the Model XM128 modem or ISDN, same as the command ATH.  
Hang up the analog adapter, PHONE 1.  
Hang up the analog adapter, PHONE 2.  
Display inquired information  
I0  
I1  
Display product code, same as ATI Results:  
1291  
1292  
1293  
(USA)  
(DSS1)  
(1TR6)  
Display product information and ROM checksum  
Results: XM128 <switch>: V x.xx  
where <switch>= USA, DSS1, or 1TR6  
I3  
I9  
Display link status report  
Display Microsoft PnP code  
Add-threshold for MPPP in Kbps unit  
JAn  
n=0-255  
*48  
AT Command Set Reference  
C-5  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Table C-1.  
Basic AT command set (continued)  
Command  
Options  
Function and description  
JSn  
n=0-255  
*32  
Sub-threshold for MPPP in Kbps unit  
KAxn  
KSxn  
Ln  
n=0-63  
*0  
Add-persist time interval for BOD; BOD disabled if n=0  
x= M(in Minute unit) or S(in Second unit)  
n=0-63  
*0  
Sub-persist time interval for BOD; BOD disabled if n=0  
x= M(in Minute unit) or S(in Second unit)  
n=0-3  
2 *  
Speaker volume control. The higher the value, the higher the volume.  
Mn  
M=0-2  
M0  
Speaker control.  
Speaker always off.  
M1 *  
M2  
Speaker on until call is answered.  
Speaker always on.  
Nn  
n=0-3  
3 *  
Ring volume control. The No command disables the audio ring function.  
O
Return to online state  
Pn  
n=0-6  
D channel protocol selection (USA) for American version  
Northern Telecom proprietary ISDN  
National ISDN 1 (1 SPID)  
P0  
P1  
P2  
P3  
P4  
P5  
P6  
*
National ISDN 1 (2 SPID)  
Reserved  
AT&T custom point-to-multipoint (1 SPID)  
AT&T custom point-to-multipoint (2 SPID)  
Qn  
n=0-1  
Result code displayed. See also S-register 23.7. For a description of Extended  
S-registers, refer to Table D-4 on page D-5 in Appendix D, “Status Registers  
and Result Codes."  
Q0  
Q1  
*
The Model XM128 modem returns result code.  
The Model XM128 modem does not return result code.  
Set bit b of S-register r to value n. The value n is a binary digit 0 or 1.  
Display value of bit b of S-register r.  
Sr.b=n  
Sr.b?  
Sr=n  
Set S-register r to value n, which must be a decimal number between 0 and  
255.  
Sr?  
Display value stored in S-register r.  
C-6  
AT Command Set Reference  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Basic AT command set (continued)  
Table C-1.  
Command  
Options  
Function and description  
SPIDn=m  
User enters Service Profile ID (SPID) m, for USA switches.  
First SPID number  
SPID0  
SPID1  
SPID?  
UPX  
Vn  
Display the SPID setting(s).  
Download firmware to the flash EPROM using X-modem Protocol.  
Sets display type for result codes. See also S-register 23.6. For a description  
of Extended S-registers, refer to Table D-4 on page D-5 in Appendix D, “Status  
Registers and Result Codes."  
V0  
Displays result code in numeric form. See also S-register 35.7 and the result  
code table of ATXn. For a description of Extended S-registers, refer to  
Table D-4 on page D-5 in Appendix D, “Status Registers and Result Codes."  
V1 *  
Xn  
Zn  
n=0-7  
5 *  
Result code options. See the options table. See also S-registers 23.3 to 23.5.  
For a description of Extended S-registers, refer to Table D-4 on page D-5 in  
Appendix D, “Status Registers and Result Codes."  
n=0-4  
Resets the Model XM128 modem and sets power-on profile. See also  
S-registers15.5 to 15.7. For a description of Extended S-registers, refer to  
Table D-4 on page D-5 in Appendix D, “Status Registers and Result Codes."  
Zn  
Z4  
Resets the Model XM128 modem and loads user profile n (0-3).  
Resets the Model XM128 modem and loads factory settings.  
Basic command summary help  
$
Description of ATI3 Output  
The Link Status Report output is displayed on the screen as follows:  
NETGEAR ISDN Modem LINK STATUS REPORT  
Connect DTE Speed  
Error Control Level  
Protocol Link Speed  
Octets Received  
Octets Sent  
:
:
:
: 0  
: 0  
:
Cause  
Cause Value  
HDLC FCS Error  
: 0  
: 0  
HDLC Receive Over-run : 0  
HDLC Transmit Under-run : 0  
AT Command Set Reference  
C-7  
 
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Table C-2 shows the outputs for the AT13 commands.  
Table C-2.  
ATI3 command output  
Output parameter  
Output value description  
Connect DTE Speed  
Error Control Level  
Protocol Link Speed  
Octets Received  
Octets Sent  
Current online DTE speed  
Error control protocol used for current session  
Current online DCE speed, line speed  
Number of data octets received from remote  
Number of data octets sent to remote  
Cause  
Verbose disconnection reason for the last session  
Numerical disconnection reason for the last session  
Cause Value  
HDLC FCS Error  
Errors in frame (block) checksum (If there were many FCS  
Errors, you may have experienced problems on the line.)  
HDLC Transmit Under-run  
HDLC Receive Over-run  
For processor power measurement of the Model XM128 modem  
For processor power measurement of the Model XM128 modem  
Table C-3 lists the extended AT& command set.  
Table C-3.  
Extended AT& command set  
Command  
Options  
Function and description  
&Cn  
Carrier Detect (CD) options. See also S-register 21.4. For a description of  
Extended S-registers, refer to Table D-4 on page D-5 in Appendix D, “Status  
Registers and Result Codes."  
&C0  
CD is always on. See also S-register S42.7.  
&C1 *  
CD tracks presence of carrier. See also S38.3 and S42.7. For a description  
of Extended S-registers, refer to Table D-4 on page D-5 in Appendix D,  
“Status Registers and Result Codes."  
C-8  
AT Command Set Reference  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
Extended AT& command set (continued)  
Table C-3.  
Command  
Options  
Function and description  
&Dn  
25. For a description of Extended S-registers, refer to Table D-4 on page D-5  
in Appendix D, “Status Registers and Result Codes."  
&D0  
&D1  
Ignore DTR signal; assume DTR is always on.  
108.1, DTR OFF-ON transition causes dialing of the default number. See  
also the command AT*Dn and S48.4. For a description of Extended  
S-registers, refer to Table D-4 on page D-5 in Appendix D, “Status Registers  
and Result Codes."  
&D2 *  
&D3  
hang up.  
Same as &D2, but DTR OFF causes the Model XM128 modem to hang up  
and reset from profile 0.  
&En  
B channel line speed for ISDN data call. See also S-register 118.2. For a  
description of Extended S-registers, refer to Table D-4 on page D-5 in  
Appendix D, “Status Registers and Result Codes."  
&E0 *  
&E1  
64 Kbps.  
56 Kbps (Default for American ISDN).  
Load factory settings to RAM as active configuration.  
&F  
&Hn  
Data flow control, DTE/DCE. See also S-registers 27.3 to 27.5. For a  
description of Extended S-registers, refer to Table D-4 on page D-5 in  
Appendix D, “Status Registers and Result Codes."  
&H0  
&H3 *  
&H4  
Hardware (CTS/RTS) flow control is disabled.  
Software (XON/XOFF) flow control is disabled.  
&Jn  
Bundle selection. See also S-registers 87.5, 87.6 and 100. For a description  
of Extended S-registers, refer to Table D-4 on page D-5 in Appendix D,  
“Status Registers and Result Codes."  
&J0 *  
&J1  
Bundle connection is disabled.  
Bundle connection is enabled in answer mode only.  
Bundle connection is enabled in call mode only.  
Bundle connection is enabled in both directions.  
&J2  
&J3  
AT Command Set Reference  
C-9  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Table C-3.  
Extended AT& command set (continued)  
Command  
Options  
Function and description  
&Knn  
V.120/X.75 compression control. The command &K must be followed by two  
digits. See also S-register 83.2. For a description of Extended S-registers,  
refer to Table D-4 on page D-5 in Appendix D, “Status Registers and Result  
Codes."  
&K00  
&K44  
Disables V.42bis.  
Enables V.42bis.  
&Ln  
Analog port selection during call answering. See also S-register 84.5. For a  
description of Extended S-registers, refer to Table D-4 on page D-5 in  
&L0  
&L1  
Sets priority to analog port, PHONE 1.  
Sets priority to analog port, PHONE 2.  
&On  
Set default call type for conventional dialing commands. See also S-register  
83.4 and 83.5.For a description of Extended S-registers, refer to Table D-4  
on page D-5 in Appendix D, “Status Registers and Result Codes."  
&O0  
ATDs, ATDPs, and ATDTs default to make calls for analog adapter,  
PHONE 2.  
&O2  
&O3  
ATDs, ATDPs, and ATDTs default to make ISDN data calls.  
ATDs, ATDPs, and ATDTs default to make calls for the analog adapter,  
PHONE 1.  
&Sn  
description of Extended S-registers, refer to Table D-4 on page D-5 in  
Appendix D, “Status Registers and Result Codes."  
&S0 *  
&S1  
DSR is overridden; DSR is always on.  
DSR according to CCITT (ITU-TSS). See also S-registers 41.5 and 44.4. For  
a description of Extended S-registers, refer to Table D-4 on page D-5 in  
Appendix D, “Status Registers and Result Codes."  
&Tn  
&Vn  
Model XM128 modem testing.  
Initiates ISDN loopback test.  
&T9  
&T10  
Initiates ISDN loopback with self-test.  
Views profile settings.  
&V0  
&V1-4  
&V5  
&V6  
&V7  
Views current active settings.  
Views the (n-1)th user profile settings.  
Views factory default settings.  
Views analog adapter, PHONE 1 setting.  
Views analog adapter, PHONE 2 setting.  
C-10  
AT Command Set Reference  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Extended AT& command set (continued)  
Table C-3.  
Command  
Options  
Function and description  
&Wn  
n=0-3  
Writes current settings to user profile n in nonvolatile RAM. See also  
S-register 35.6. For a description of Extended S-registers, refer to Table D-4  
on page D-5 in Appendix D, “Status Registers and Result Codes."  
&Z?  
Display all the phone numbers stored in nonvolatile RAM.  
&Zn=s  
n=0-39  
n=0-7  
Write phone number/s to NVRAM at location n (n=0-39); use AT*Dn or  
ATS29=n to set the default dial pointer.  
&ZIn=s  
s=phone number  
MSN setting. Assign the phone number (including subaddress, if any) for  
various B channel protocols. In answer mode, these numbers are compared  
with the received called_party_number and called_party_subaddress  
information. The call is accepted using the specific protocol if the assigned  
number of this protocol matches with the called_party_number.  
n=0  
n=1  
n=2  
n=3  
n=4  
n=6  
Assigns multiple subscriber number (MSNs) phone number for X.75.  
Assigns MSNs phone number for V.110.  
Assigns MSNs phone number for V.120.  
Assigns MSNs phone number for PPP, MPPP.  
Assigns MSNs for ISDN data, protocol auto-detection.  
Assigns the phone number s for analog adapter,  
PHONE 1.  
n=7  
Assigns the phone number s for the analog adapter, PHONE 2.  
&ZI?  
Displays the phone number (including subaddress, if any) for various B  
channel protocols.  
&ZO?  
Displays the &ZOn setting.  
&ZOn=x  
Writes own phone number (including subaddress, if any). The number  
specified is used as the calling party number while dialing. Value for n:  
I = ISDN data  
A = analog adapter, PHONE 1  
B = analog adapter, PHONE 2  
AT Command Set Reference  
C-11  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Table C-4 lists the extended AT* command set.  
Table C-4.  
Extended AT* command set  
Command Options  
Function and description  
*Cn  
n=0-3  
Character length, including start, stop and parity bit. See also S-register 15.3 and  
15.4. For a description of Extended S-registers, refer to Table D-4 on page D-5 in  
Appendix D, “Status Registers and Result Codes."  
*C0 *  
*C1  
10-bit character length.  
9-bit character length.  
8-bit character length.  
*C2  
*C3  
*Dn  
*Gn  
n=0-39  
Sets default dial pointer at telephone directory location n. See also S-register 29.  
For a description of Extended S-registers, refer to Table D-4 on page D-5 in  
Appendix D, “Status Registers and Result Codes."  
*D0 *  
See also S35.4 and S38.0. For a description of Extended S-registers, refer to  
Table D-4 on page D-5 in Appendix D, “Status Registers and Result Codes."  
Security function selection. See also S-registers 36.5 to 36.7. For a description of  
Extended S-registers, refer to Table D-4 on page D-5 in Appendix D, “Status  
Registers and Result Codes."  
*G3  
*G4  
*G5  
Enables type 2 security, with password check.  
Enables type 2 security, with password check and callback.  
Enables type 2 security, with password check and callback; remote site enters the  
callback number.  
*GCn  
n=0-1  
*GC0  
*GC1  
n=0-4  
n=0-39  
Callback function selection.  
Disables callback function.  
Enables callback function.  
*HCn=s  
*Hn  
*HS  
*T  
Assigns callback phone number, s to storage location n.  
Modifies user password table at location n.  
Modifies supervisory password (Default: NETGEAR).  
Recalls the last CND (Caller ID) information.  
Views the Password table.  
*V  
*VC  
Views the Callback Number table.  
C-12  
AT Command Set Reference  
 
   
Appendix D  
Status Registers and Result Codes  
This appendix describes the purpose and application of status registers and result codes for the  
Model XM128 ISDN Digital Modem.  
Status registers (S-registers) contain values that determine and reflect how your Model XM128  
modem operates and executes commands. You can read the values and change them by using  
either terminal commands or the panel controls with the same results.  
Every user profile corresponds to a separate set of S-register values, but when S-registers are  
mentioned in this guide, the reference is to those that correspond to the active profile. If you want  
to read or change the values in a profile that is currently inactive, you must first recall that profile  
to make it active.  
S0 to S11 are standard AT S-registers, and S12 to S124 are mostly bitmap configured. Changes in  
the bitmap configuration can have the same effect as issuing AT commands. However, NETGEAR  
recommends that you use equivalent AT commands.  
Viewing and Setting S-Registers  
Several AT commands are used to view the values stored in the S-registers. To view S-registers,  
follow these steps:  
1. Type the AT command ATSr? to display the values stored in S-registers.  
The S-register values may be displayed in either decimal or hexadecimal format when using  
the commands. Bit 3 of S-register 84 sets the numbering system to be used for display:  
ATS84.3=0 for decimal format.  
ATS84.3=0 for hexidecimal format.  
Status Registers and Result Codes  
D-1  
 
         
Reference Guide for the Model XM128 ISDN Digital Modem  
2. Type the &Vn command AT&Vn to view all of the S-register settings.  
To view different S-register settings, use the following for n:  
0 for viewing S-register settings for current active profile  
1 to 4 for viewing settings for user profile number (n-1)  
5 for viewing the factory default settings  
6 for viewing the setting of PHONE 1  
7 for viewing the setting of PHONE 2  
3. Type the command ATSr.b? to display the value of bit b of S-register r.  
Setting S-Registers  
In the commands to change the value in S-register r and to change the value in a specific bit of  
S-register r, n is a decimal number in the given range. Although the first command modifies all bits  
in the S-register simultaneously, the second command lets you change bit b without affecting other  
bits in this S-register. When using ATSr=n, do a conversion to or from the binary number to find  
out which bits to manipulate.  
To change the S-register values, follow these steps:  
1. Type the command ATSr=n (range 0-255) to change the value in S-register r to value n.  
2. Type the command ATSr.b=n (range 0-1) to change the value in a specific bit (b) of  
S-register r.  
Examples for Setting S-Registers  
Note: The values used in the examples differ from the actual values in the S-register and  
are used for demonstration purposes only.  
If you want to set S38 bit 3 to 1 for a specific application, use either the simple command  
ATS38.3=1 or use the difficult method outlined in the following steps:  
1. Read the value from S38 using the ATS38? command.  
D-2  
Status Registers and Result Codes  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
2. Use Table D-1 to convert the decimal bit value to binary.  
Table D-1. Binary conversion table  
Binary  
value  
Decimal  
value  
Hexadecimal  
value  
Bit  
0
1
2
3
4
5
6
7
00000001  
00000010  
00000100  
00001000  
00010000  
00100000  
01000000  
10000000  
1
$01  
$02  
$04  
$08  
$10  
$20  
$40  
$80  
2
4
8
16  
32  
64  
128  
3. Use Table D-2 to perform a logic OR operation with the value to set bit 3 to 1 (binary).  
Table D-2.  
Setting bit 3  
Example 1  
Example 2  
Binary  
Operation  
Decimal Hexadecimal  
Decimal  
Hexadecimal  
Binary  
OR  
10001000  
00001000  
10001000  
00001000  
11110111  
10001000  
10000000  
136  
8
$88  
$08  
$88  
$08  
$F7  
$88  
$80  
01000000  
00001000  
01001000  
00001000  
11110111  
01000000  
01000000  
64  
8
$40  
$08  
$48  
$08  
$F7  
$40  
$40  
136  
8
72  
8
NOT  
AND  
247  
136  
128  
247  
64  
64  
4. Use Table D-2 to invert the value using a logic NOT operation and then perform a logic  
AND operation to set bit 3 to 0 (binary).  
5. Using the resulting decimal value, type the ATS38=n command to set the register.  
Status Registers and Result Codes  
D-3  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
S-Register Descriptions  
In most bitmapped S-registers, the default bit value is 0 (which is the normal situation) and only  
the nondefault situation is described. Some reserved bits are for factory use, and the user should  
not change them. Table D-3 describes each basic S-register. Values followed by an asterisk (*) are  
the factory default settings.  
Table D-3.  
Basic S-registers ATSn=x  
Function and description  
Command  
Default  
S0=  
Sets the number of rings on which the Model  
XM128 modem answers; 0 value disables  
auto-answer.  
000  
S1=  
S2=  
Counts and stores number of rings from an  
incoming call.  
000  
043  
Defines escape code character, default [+]  
(43 dec.).  
S3=  
S4=  
S5=  
S7=  
Defines ASCII carriage return.  
Defines ASCII line feed.  
013  
010  
008  
060  
Defines ASCII backspace.  
Sets duration, in number of seconds, that the  
Model XM128 modem waits for a carrier.  
S8=  
Sets duration, in seconds, for the pause and  
repeat commands. For more information, refer  
to Table C-1 on page C-2.  
002  
D-4  
Status Registers and Result Codes  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
Table D-4 describes each extended S-register. Defaults are indicated by a plus sign (+) in the  
Default or reference column of the table.  
Table D-4.  
Extended S-registers ATSn=x  
Function and  
description  
Default or  
reference  
Command  
Bit  
Decimal  
Hexadecimal  
S15=  
Bitmapped register  
Even parity  
+130  
0,1  
0
1
0
1
Odd parity  
2
2 *  
0 *  
4
No parity  
2
0
1 stop bit  
4
2 stop bits  
4,3  
0
0 *  
8
10-bit character length  
11-bit character length  
9-bit character length  
8-bit character length  
*C0  
*C1  
*C2  
*C3  
Z0  
8
16  
24  
0
10  
18  
0
7-5  
Profile 0 as active settings after  
power on  
32  
20  
Profile 1 as active settings after  
power on  
Z1  
Z2  
Z3  
Z4  
64  
40  
Profile 2 as active settings after  
power on  
96  
60  
Profile 3 as active settings after  
power on  
128  
80 *  
Factory default as active settings  
after power on  
S16=  
S18=  
Test status register  
+000  
&T0  
&T9  
0
0
9
A
No test in progress  
9
Loopback test in progress  
10  
Loopback with self-test in progress &T10  
Forces the Model XM128 modem +000  
to fix baud rate when idle  
0 *  
Disables fixed baud function  
n+1  
Enables baud rate fixing at idle,  
n=0-15 baud rate value settings (n)  
the same as S20 value  
Status Registers and Result Codes  
D-5  
 
   
Reference Guide for the Model XM128 ISDN Digital Modem  
Table D-4.  
Extended S-registers ATSn=x (continued)  
Function and  
description  
Default or  
reference  
Command  
Bit  
Decimal  
Hexadecimal  
S20=  
DTE speed (bps) auto-detected  
from AT command  
+003  
0
0
1
3
4
5
9
B
C
D
E
F
230400 bps  
115200 bps  
57600 bps  
1
3
4
38400 bps  
5
19200 bps  
9
9600 bps  
11  
12  
13  
14  
15  
4800 bps  
2400 bps  
1200 bps  
460800 bps  
921600 bps  
Bitmapped register  
Speaker is always off.  
S21=  
1-2  
0
2
0
2
M0  
M1  
Speaker is on until carrier is  
detected.  
4
0
8
4
0
8
Speaker is always on.  
DSR is always on.  
M2  
3
4
&S0  
&S1  
According to CCITT. See also  
S-register S44.4 and S41.5.  
0
0
CD is always on.  
&C0  
16  
10  
CD tracks presence of data carrier. &C1  
See also S-register 38.3.  
D-6  
Status Registers and Result Codes  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Extended S-registers ATSn=x (continued)  
Table D-4.  
Command  
Function and  
description  
Default or  
reference  
Bit  
Decimal  
Hexadecimal  
S21=  
(continued)  
6-7  
0
0
Assumes that Data Terminal  
Ready (DTR) is always on.  
&D0  
64  
40  
80  
108.1, DTR off-on transition  
causes dial of the default number.  
&D1  
128  
108.2, DTR off causes the Model &D2  
XM128 modem to hang up and  
return to command state.  
192  
C0  
108.2, DTR off causes the Model &D3  
XM128 modem to hang up and  
resets the Model XM128 modem  
to profile #0 after DTR dropped.  
S23=  
Bitmapped register  
+105  
E0  
0
2
0
1
0
0
1
0
Command echo is disabled.  
Command echo is enabled.  
E1  
Insertion is not allowed during a  
PHONE call.  
4
4
Insertion is allowed during a  
PHONE call.  
3-5  
0
0
ATX0 (see result code table)  
ATX1 dec hex AT  
ATX2 40 28 X5  
ATX3 48 30 X6  
ATX4 56 38 X7  
8
8
16  
24  
32  
0
10  
18  
20  
0
6
Displays result code in numeric  
format. See also S-register S35.7.  
V0  
V1  
64  
40  
Displays result code in verbose  
format.  
Status Registers and Result Codes  
D-7  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Table D-4.  
Extended S-registers ATSn=x (continued)  
Function and  
description  
Default or  
reference  
Command  
Bit  
Decimal  
Hexadecimal  
S24=  
Bitmapped register.  
0-1  
2
0-3  
0
0-3  
0
Ring volume control, in increments N0-3  
of 1 in decimal value  
Ignore S21.1-2 when PHONE 1  
keypad is dialed.  
4
4
Do not ignore S21-2 when PHONE  
1 keypad is dialed.  
3
0
0
Ignore S21.1-2 when PHONE 2  
keypad is dialed.  
8
8
Do not ignore S21-2 when PHONE  
2 keypad is dialed.  
5-4  
Speaker volume control, in  
L0-3  
increments of 16 in decimal value  
S25=  
S27=  
0-255  
0-FF  
Specify the time delay that DTR  
signal needs to be off before it  
is recognized, in 10 ms units. If  
S25=0, the delay time is set to  
4 ms.  
+000  
Bitmapped register  
3-5  
0
0
Flow control is disabled.  
&H0  
24  
32  
18  
20  
Hardware (RTS/CTS) flow control. &H3  
Software (XON/XOFF) flow  
control.  
&H4  
40  
28  
Reserved.  
&H5  
S29=  
0-  
39  
0-  
39  
Sets default dial PHONE number  
pointer; uses AT&Zn=s to store  
PHONE numbers.  
+000 *D  
S31=  
S32=  
0-255  
0-255  
0-FF  
0-FF  
Holds the ASCII decimal value of  
the XON.  
+017  
Holds the ASCII decimal value of +019  
the XOFF.  
D-8  
Status Registers and Result Codes  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Extended S-registers ATSn=x (continued)  
Table D-4.  
Function and  
description  
Default or  
reference  
Command  
Bit  
Decimal  
Hexadecimal  
S35=  
Bitmapped register  
4
7
16  
10  
80  
When Data/Voice is pressed,  
the Model XM128 modem dials the  
default number.  
128  
Enable extended numerical result  
codes from 50 -71 when an error  
corrected connection is made. Use  
with ATV0 (see result code table).  
S38=  
Bitmapped register  
+000  
0
3
1
8
1
8
Repeatedly dialing default number. *Dn S29  
DCD on/off sequence follows UNIX &C1 S21.4  
standard, DCD high before  
connect message is sent, DCD  
off after last DCE response is sent.  
S40=  
S41=  
S42=  
Bitmapped register  
+000  
1
3
2
8
8
2
8
8
No result code displayed in answer Q2  
mode.  
Bitmapped register.  
+000  
Enables CCITT signals 140 and  
141 on EIA-232D interface.  
Bit  
3
Bitmapped register  
+000  
Disables escape sequence code  
in answer mode.  
5
6
32  
64  
20  
40  
Disables Data/Voice button.  
Disables <RINGING> result code. Xn  
S44=  
S56=  
Bitmapped register  
+000  
3
4
8
8
ATDSn initiates auto-dial of the  
stored numbers consecutively until  
connection is made.  
DSn  
16  
10  
DSR follows DTR. See also  
S-register S41.5.  
&S1  
0-255  
0-FF  
Hook flash detect time for analog  
adapter (POTS port); units 10ms.  
+050  
Status Registers and Result Codes  
D-9  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Table D-4.  
Extended S-registers ATSn=x (continued)  
Function and  
description  
Default or  
reference  
Command  
Bit  
Decimal  
Hexadecimal  
S64=  
0-255  
0-FF  
Security callback timer in unit of 1 +050  
second.  
S80=  
Bitmapped register  
+000  
4
0 *  
16  
0
Do not send low-layer compatibility  
information for PHONE 2 (Model  
XM128 modem) or internal fax/  
modem (2864I).  
10  
Send low-layer compatibility for  
PHONE 2 (Model XM128 modem)  
or internal fax/modem (2864I).  
6
7
0 *  
64  
0 *  
0
Do not send low-layer compatibility  
information for ISDN data call.  
40  
0
Send low-layer compatibility for  
ISDN data call.  
Do not send low-layer compatibility  
information for PHONE 1 (Model  
XM128 modem) or analog adapter  
(2864I).  
128  
80  
Send low-layer compatibility for  
PHONE 1 (Model XM128 modem)  
or analog adapter (2864I).  
D-10  
Status Registers and Result Codes  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Extended S-registers ATSn=x (continued)  
Table D-4.  
Function and  
description  
Default or  
reference  
Command  
Bit  
Decimal  
Hexadecimal  
S82=  
ISDN B channel protocol  
V.120 64000  
Bn  
60  
61  
62  
63  
64  
65  
72  
73  
74  
75  
76  
V.120 56000  
X.75 64000 Transparent  
X.75 56000 Transparent  
X.75 64000 T.70  
X.75 56000 T.70  
V.110 64000  
V.110 56000  
PPP async to sync 64K  
PPP async to sync 56K  
SLIP to sync HDLC conversion  
64K  
77  
SLIP to sync HDLC conversion  
56K  
S83=  
Bitmapped register  
+000  
CP0  
0
0
0
1
0
4
0
Disables loopback 4 test.  
Enables loopback 4 test.  
ISDN without V.42bis  
1
CP1  
2
0
&K00  
&K44  
&O0  
4
ISDN with V.42bis, if applicable  
4-5  
0 *  
ATDs, ATDPs, and ATDTs are  
mapped to ATDMs.  
32  
48  
20  
30  
ATDs, ATDPs, and ATDTs are  
mapped to ATDIs.  
&O2  
&O3  
ATDs, ATDPs, and ATDTs are  
mapped to ATDBs.  
Status Registers and Result Codes  
D-11  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Table D-4.  
Extended S-registers ATSn=x (continued)  
Function and  
description  
Default or  
reference  
Command  
Bit  
Decimal  
Hexadecimal  
S84=  
3
8
8
Displays S-register value in hex  
format.  
4
5
0 *  
0
Indicates Caller ID after the 1st  
RING message.  
16  
0
10  
0
Disables Caller ID indication.  
PHONE 1 (Model XM128 modem) &L0  
or analog port (2864I) has higher  
priority for answering an analog  
call.  
32  
20  
PHONE 2 (Model XM128 modem) &L1  
or internal device (2864I) has  
higher priority for answering an  
analog call.  
S85=  
DCA function  
0
0
1
*0  
*1  
*0  
0
DCA function is disabled.  
DCA function is enabled.  
Add-persist time interval.  
S85b1-6 is in Second unit.  
S85b1-6 is in Minute unit.  
CE0  
CE1  
KAxn  
KASn  
KAMn  
Pn  
1-6  
7
0
128  
80  
S86=  
D channel protocol selection  
(USA); this register is valid only for  
American version.  
0
0
Northern Telecom proprietary  
ISDN.  
1
2
3
4
5
1
2
3
4
5
National ISDN 1 (1 SPID mode).  
National ISDN 1 (2 SPID mode).  
Reserved.  
AT&T proprietary point-to-point.  
AT&T proprietary  
point-to-multipoint (1 SPID mode).  
6
6
AT&T custom point-to-multipoint  
(2 SPID mode).  
D-12  
Status Registers and Result Codes  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Extended S-registers ATSn=x (continued)  
Table D-4.  
Function and  
description  
Default or  
reference  
Command  
Bit  
Decimal  
Hexadecimal  
S87=  
5-6  
0 *  
32  
0
Bundle connection is disabled.  
&Jn  
20  
Bundle connection is enabled in  
answer mode only.  
64  
96  
40  
60  
Bundle connection is enabled in  
call mode only.  
Bundle connection is enabled in  
both directions.  
S89=  
Bitmapped register  
5
6
0
0
Disables the metering pulse of  
analog adapter, PHONE 2.  
32  
0
32  
0
Enables the metering pulse of  
analog adapter, PHONE 2.  
Disables the metering pulse of  
analog adapter, PHONE 1.  
64  
40  
Enables the metering pulse of  
analog adapter, PHONE 1.  
S100=  
S102=  
B channel bundling protocol  
selection.  
0 *  
1
0
1
Multiple Link Protocol (MLP).  
cFossil channel bundling, for  
European switches only (cFos).  
Outgoing ISDN data type; value  
has the same definition as S82.  
Bnn  
Status Registers and Result Codes  
D-13  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Table D-4.  
Extended S-registers ATSn=x (continued)  
Function and  
description  
Default or  
reference  
Command  
Bit  
Decimal  
Hexadecimal  
S104+n=  
Outgoing service additional (for  
1TR6 only) information:  
n=0, analog adapter, PHONE 2  
n=2, ISDN data  
n=3, analog adapter, PHONE 1  
1
2
7
1
2
7
Fernsprechen  
a/b - Dienste  
Daten bertragung 64 Kbps. The  
defaults are:  
* s104=1 - for a/b adapter 2  
* s105= - reserved  
* s106=7 - for ISDN data  
* s107=1 - for a/b adapter 1  
S108+n=  
Outgoing service additional (for  
1TR6 only) information:  
n=0, analog adapter, PHONE 2  
n=2, ISDN data  
n=3, analog adapter, PHONE 1  
SI=1  
SI=2  
1
2
2
3
4
1 *  
2
ISDN-Fernsprechen 3.1 KHz  
Fernsprechen analog  
Fax Gruppe 3  
2
3 *  
4
Daten Über Modem  
Btx Über Modem  
D-14  
Status Registers and Result Codes  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Extended S-registers ATSn=x (continued)  
Table D-4.  
Command  
Function and  
description  
Default or  
reference  
Bit  
Decimal  
Hexadecimal  
S108+n=  
(continued)  
SI=7  
0
00  
Daten bertragung 64 Kbps  
(X.75 SLP)  
192  
64  
C0  
40  
00  
20  
00  
10  
00  
08  
C0  
C3  
C4  
C5  
C6  
C7  
40  
A0  
A0  
A3  
A4  
A5  
A6  
A7  
A8  
A9  
AA  
AF  
Async. V.110  
Extensions of async.  
Number of data bits: 8  
Number of data bits: 7  
Number of stop bits: 1  
Number of stop bits: 2  
No parity  
0
32  
0
16  
0
8
Even parity  
192  
195  
196  
197  
198  
199  
64  
1200 bps  
2400 bps  
4800 bps  
9600 bps  
14400 bps  
19200 bps  
38400 bps  
160  
160  
163  
164  
165  
166  
167  
168  
169  
170  
175  
Sync. V.110  
1200 bps  
2400 bps  
4800 bps  
9600 bps  
14400 bps  
19200 bps  
48000 bps  
56000 bps  
56000 bps for 56K network  
In-band negotiation  
Status Registers and Result Codes  
D-15  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Table D-4.  
Extended S-registers ATSn=x (continued)  
Function and  
description  
Default or  
reference  
Command  
Bit  
Decimal  
Hexadecimal  
S108+n=  
High-layer compatibility  
(Non-1TR6)  
n=0, analog adapter,PHONE 2  
n=2, ISDN data  
n=3, analog adapter, PHONE 1  
0 *  
0
No high-layer compatibility  
information element is sent.  
1
1
Telephone  
4
4
Facsimile Group 2/3  
Teletex service (Rec.F.220)  
Teletex service (Rec.F.200)  
40  
49  
50  
28  
31  
32  
Information interworking for Video  
Services (Rec.F.300 T.110)  
53  
56  
35  
38  
Telex service (Rec.F.60)  
Message handling systems (MHS)  
(Rec.X.400 series)  
65  
41  
OSI application (Rec.X.200 series)  
I-field data length (MSB byte)  
I -field data length (LSB byte)  
V.110 user rate  
S114=  
S115=  
S117=  
B1n  
D-16  
Status Registers and Result Codes  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Extended S-registers ATSn=x (continued)  
Table D-4.  
Command  
Function and  
description  
Default or  
reference  
Bit  
Decimal  
Hexadecimal  
S118=  
(see  
AT&ZIn=s)  
Bit  
0
Decimal  
Hexadecimal  
0
1
0
0
1
0
Enables dial-in call.  
Disables dial-in call (dial out only).  
2
Default B channel line speed is  
64 Kbps for ISDN data call.  
&E0  
&E1  
4
4
0
Default B channel line speed is  
56 Kbps for ISDN data call.  
4
0 *  
Uses 3.1KHz bearer service  
whenever possible for analog  
adapter, PHONE 2.  
16  
0 *  
32  
10  
0
Uses speech bearer service  
whenever possible for analog  
adapter, PHONE 2.  
5
6
Uses 3.1KHz bearer service  
whenever possible for analog  
adapter, PHONE 1.  
20  
Uses speech bearer service  
whenever possible for analog  
adapter, PHONE 1.  
0 *  
64  
0
Enables analog adapter to accept  
global calls.  
40  
Forbids analog adapter to accept  
global calls with MSN unmatched.  
7
0
1
0 *  
128  
0 *  
1
0
Enables analog incoming calls.  
Rejects analog incoming calls.  
Disables callback function.  
Enables callback function.  
80  
0
S119=  
*GC  
1
0 *  
0
Disables point-to-point signaling  
DDI function.  
2
2
Enables point-to-point signaling  
DDI function.  
Status Registers and Result Codes  
D-17  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Table D-4.  
Command  
Extended S-registers ATSn=x (continued)  
Function and  
description  
Default or  
reference  
Bit  
Decimal  
Hexadecimal  
S119=  
(continued)  
2
0 *  
0
Disables point-to-multipoint  
signaling DDI function.  
4
4
0
8
Enables point-to-multipoint  
signaling DDI function.  
3
0 *  
8
Inbound call ignored when no  
MSN (EAZ) is matched.  
Inbound call accepted using  
default protocol when no MSN  
(EAZ) is matched.  
4
5
0 *  
16  
0
V.110 user rate = 19200 bps if DTE  
speed is greater than 19200 bps.  
10  
V.110 user rate = 38400 bps if DTE  
speed is greater than 38400 bps.  
0 *  
32  
0
Enables normal MSN function.  
&ZIn  
20  
Treats the number assigned by  
&ZI=n... as subaddress, and  
matches with the called party  
subaddress for inbound call  
routing.  
S120=  
S121=  
S122=  
S123=  
S124=  
Accumulated charging unit (MSB  
byte) for B1 channel.  
Accumulated charging unit (LSB  
byte) for B1 channel.  
Accumulated charging unit (MSB  
byte) for B2 channel.  
Accumulated charging unit (LSB  
byte) for B2 channel.  
Empties IP packet interval for PPP. +000  
Units of 1 sec.  
0-255  
0-FF  
*0  
S125=  
1-6  
7
Sub-persist time interval.  
S125b1-6 is in second unit.  
S125b1-6 is in minute unit.  
KSxn  
KSSn  
KSMn  
0
*0  
128  
80  
D-18  
Status Registers and Result Codes  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Extended S-registers ATSn=x (continued)  
Table D-4.  
Function and  
description  
Default or  
reference  
Command  
Bit  
Decimal  
Hexadecimal  
S126=  
0-255  
0-FF  
Add-threshold for BOD in Kbps  
unit  
JAn,+48  
S127=  
0-255  
0-FF  
Sub-threshold for BOD in Kbps  
unit  
JSn,+32  
ATXn Result Code Option Table  
Table D-5 lists the different options available when setting the ATXn command. The default value  
for n is 5 when the Model XM128 modem is shipped.  
Table D-5.  
ATXn command setting options  
ATV0 ATV1  
X0  
X1  
X2  
X3  
X4  
X5  
X6  
X7  
0
OK  
V
V
V
V
V
V
V
V
V
V
%
V
V
V
V
V
%
V
V
V
V
V
V
%
V
V
V
$
V
V
V
$
V
V
V
V
$
$
$
$
$
$
$
$
V
#
V
V
V
#
V
V
V
V
#
#
#
#
#
#
#
#
1
CONNECT  
V
@
V
2
RING  
V
3
NO CARRIER  
ERROR  
V
V
4
V
V
5
CONNECT 1200  
NO DIAL TONE  
BUSY  
%
V
@
V
6
7
V
V
V
8
NO ANSWER  
RINGING*  
V
V
V
9
V
V
V
10  
11  
12  
14  
15  
16  
17  
18  
19  
CONNECT 2400  
CONNECT 4800  
CONNECT 9600  
CONNECT 19200  
CONNECT 7200  
CONNECT 12000  
CONNECT 14400  
CONNECT 16800  
CONNECT 38400  
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
@
@
@
@
@
@
@
@
@
Status Registers and Result Codes  
D-19  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
Table D-5.  
ATXn command setting options (continued)  
ATV0 ATV1  
X0  
X1  
X2  
X3  
X4  
X5  
X6  
X7  
20  
21  
22  
23  
24  
25  
26  
27  
28  
29  
30  
31  
32  
33  
34  
35  
36  
37  
38  
39  
40  
41  
42  
43  
44  
45  
46  
47  
CONNECT 57600  
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
CONNECT 76800  
CONNECT 115200  
CONNECT 230400  
CONNECT 460800  
CONNECT 921600  
CONNECT 307200  
CONNECT 153600  
CONNECT 102400  
CONNECT 61440  
CONNECT 51200  
CONNECT 62400  
CONNECT 124800  
CONNECT 62400  
CONNECT 41600  
CONNECT 31200  
CONNECT 249600  
CONNECT 20800  
CONNECT 33600  
CONNECT 28800  
CONNECT 26400  
CONNECT 24000  
CONNECT 21600  
CONNECT 48000  
CONNECT 56000  
CONNECT 64000  
CONNECT 112000  
CONNECT 128000  
$
#
$
$
$
$
$
$
$
$
$
$
#
#
#
#
#
#
#
#
#
#
* Use S42.6 to disable RINGING result code  
D-20  
Status Registers and Result Codes  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Result Code Chart Symbol Reference  
Table D-6 lists the result codes.  
Table D-6.  
Result code chart  
V
Supported  
%
Reports the DTE Speed as: <cr><lf>CONNECT  
DTE_Speed<cr><lf>  
@
CONNECT DTE_Speed/Protocol DCE_Speed/  
Error_Control **  
Example: CONNECT 115200/V120 64000 /LABD  
<cr><lf>CONNECT DCE_Speed[/Error_Code]<cr><lf>  
Example: CONNECT 64000/ARQ  
$
#
CONNECT DCE _Speed/Error_Code/Error_Control  
Example: CONNECT 64000/ARQ/V42b  
Status Registers and Result Codes  
D-21  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
Result Code Field Descriptions  
Table D-7 lists the result code field descriptions.  
Table D-7.  
Field name  
Result code field descriptions  
Possible values  
Error_Code  
NONE, ARQ  
Error_Control  
LAPB, LAPD, V42  
(This field will not show if no error  
control is negotiated)  
Data_Compression  
DCE_Speed  
DTE_Speed  
Protocol  
V42b  
All possible DCE speeds supported  
All possible DTE speeds supported  
Only ISDN protocols are listed here  
X.75  
X.75M (X.75 with MLP Bundle)  
X.75C (X.75 with cFos Bundle)  
V110  
V120  
V120M (V.120 with MLP Bundle)  
V120C (V.120 with cFos Bundle)  
SLIP  
PPP  
BTX  
D-22  
Status Registers and Result Codes  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
Connect Strings for Error Corrected Connections  
To enable the following numerical (ATV0) and verbose (ATV1) result codes when an error  
corrected connection is made, set S35 bit 7 to 1.  
Example: ATS35.7=1<enter>  
Table D-8 lists the connect strings.  
Table D-8.  
Connect strings  
ATV0  
ATV0  
ATV1  
ATV1  
50  
51  
52  
53  
54  
55  
56  
57  
58  
59  
60  
CONNECT  
61  
62  
63  
64  
65  
66  
67  
68  
69  
70  
71  
CONNECT 24000  
CONNECT 26400  
CONNECT 28800  
CONNECT 31200  
CONNECT 33600  
CONNECT 38400  
CONNECT 48000  
CONNECT 56000  
CONNECT 64000  
CONNECT 112000  
CONNECT 128000  
CONNECT 1200  
CONNECT 2400  
CONNECT 4800  
CONNECT 7200  
CONNECT 9600  
CONNECT 12000  
CONNECT 14400  
CONNECT 16800  
CONNECT 19200  
CONNECT 21600  
Status Registers and Result Codes  
D-23  
 
     
 
Appendix E  
Connector Pin Assignments  
This appendix describes the connector pinout assignments for the Model XM128 ISDN Digital  
Modem.  
The Model XM128 modem features one RJ-45 ISDN connector and two RJ-11 phone connectors.  
The RJ-45 connector labeled ISDN-S or ISDN-U is for an ISDN line connection (S/T interface or  
U interface), and the RJ-11 connectors labeled PHONE 1 and PHONE 2 (also known as analog  
adapters in European countries) are for an optional connection to analog telephone equipment such  
as a telephone, fax, or analog modem.  
RJ-45 Plug and Connector  
The RJ-45 plug and RJ-45 connector are both illustrated in Figure E-1.  
12345678  
8
1
7894FA  
Figure E-1.  
RJ-45 plug and RJ-45 connector  
Connector Pin Assignments  
E-1  
 
           
Reference Guide for the Model XM128 ISDN Digital Modem  
Table E-1 lists the pin assignments for the RJ-45 plug and RJ-45 connector for the S/T interface.  
Table E-1.  
Pin  
RJ-45 plug and RJ-45 connector pin assignments for the S/T interface  
Assignment  
1
2
3
4
5
6
7
8
Not connected  
Not connected  
RCV +  
XMT +  
XMT -  
RCV -  
- 48V  
- 48V RTN  
Table E-2 lists the pin assignments for the RJ-45 plug and RJ-45 connector for the U interface.  
Table E-2.  
Pin  
RJ-45 plug and RJ-45 connector pin assignments for the U interface  
Assignment  
1
2
3
4
5
6
7
8
Not connected  
Not connected  
Not connected  
Ring  
Tip  
Not connected  
- 48V  
- 48V RTN  
E-2  
Connector Pin Assignments  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
RJ-11 Plug and Connector  
Figure E-2 shows an RJ-11 plug and an RJ-11 connector.  
1 2 3 4  
4
1
7895MFA  
Figure E-2.  
RJ-11 plug and RJ-11 connector  
Table E-3 lists the pin assignments for RJ-11 plugs and the RJ-11 connectors for the PHONE 1 and  
PHONE 2 ports.  
Table E-3.  
Pin  
RJ-11 connector pin assignments  
Assignment  
1
2
3
4
Not connected  
Ring  
Tip  
Not connected  
Connector Pin Assignments  
E-3  
 
           
 
Appendix F  
Serial Port Interface  
This appendix provides information about the serial port interface for the Model XM128 ISDN  
RS-232 Serial Interface  
Table F-1 describes the RS-232 25-pin serial port interface for the Model XM128 modem.  
Table F-1.  
Pin number  
Serial port interface  
Signal direction  
DTE -DCE  
ITU-TSS  
EIA  
Signal/pin description  
signal name  
signal name  
1
101  
AA  
BA  
BB  
CA  
CB  
CC  
AB  
CF  
DB  
DD  
Protective ground (GND).  
Transmitted data (TXD).  
Received data (RXD).  
¤
?
2
103  
3
104  
4
105  
Request to send (RTS).  
Clear to send (CTS).  
?
5
106  
6
107  
Data set ready (DSR).  
7
102  
Signal ground (GND).  
¤
8
109  
Data carrier detected (DCD).  
Transmit clock signal (source: DCE).  
Synchronous receive clock.  
Local analog loopback test.  
15  
17  
18  
20  
114  
115  
141  
?
?
108/2108/1  
CD  
Data terminal ready (DTR).  
Connect DCE to line.  
21  
140  
Remote digital loop test.  
?
Serial Port Interface  
F-1  
 
           
Reference Guide for the Model XM128 ISDN Digital Modem  
Table F-1.  
Pin number  
Serial port interface (continued)  
Signal direction  
DTE -DCE  
ITU-TSS  
EIA  
Signal/pin description  
signal name  
signal name  
22  
24  
25  
125  
113  
CE  
DA  
Ring indicator (RI).  
Transmit clock signal (source: DTE).  
Test indicator.  
?
Asynchronous Cable Connections  
Table F-2 provides information about the asynchronous flow control cable connection.  
Table F-2.  
Asynchronous flow control cable connection  
Modem  
Signal  
To PC  
To DCE  
To  
To NeXT  
(DCE) DB25  
(DTE) DB 9  
(Null) DB25 MAC Mini 8 68,040 Mini 8  
2
TXD  
3
2
7
8
6
5
1
4
9
3
3
5
1
2
3
5
6
8
3
RXD  
2
4
RTS  
5
5
CTS  
4
6
DSR  
20  
7
7
Ground  
CD (DCD)  
DTR  
4,8  
1
4
2
1
8
20  
6,8  
20  
22  
RI  
F-2  
Serial Port Interface  
 
       
Appendix G  
ISDN Reference  
This appendix explains ISDN technical terms. The appendix also provides you with forms to assist  
you when working with your local telephone company to set up ISDN services to use with your  
Model XM128 ISDN Digital Modem.  
ISDN Overview  
ISDN is a global system that provides a variety of high-speed digital communication solutions,  
while maintaining compatibility with existing analog voice, modem, data, and fax protocols.  
ISDN is based on various standards that define communications between switches and the  
equipment that connects to the switches. These standards allow most types of equipment to  
communicate across different types of switches in every part of the world. Implementation of  
network switches by telephone companies differs from country to country.  
In North America, a separate ISDN standard called National ISDN (NI-1) is currently being  
adopted by network providers and equipment manufacturers. When fully implemented, NI-1 will  
make installation of ISDN equipment much easier. Currently, many different types of custom  
signaling protocols are used. Therefore, you must configure your Model XM128 modem for the  
type of signaling that is used by your network.  
In the rest of the world, Digital Subscriber Signaling Number 1 (DSS1) is widely deployed with  
minor differences from country to country. In Germany, there is an old ISDN system called 1TR6,  
which will be replaced gradually by DSS1.  
ISDN Reference  
G-1  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
Basic Rate Interface  
When you order a Basic Rate Interface (BRI) ISDN line, you receive what is known as the 2B+D  
service. This service provides two B channels that can transmit at 64 Kbps per channel for user  
information and a D channel that can communicate between the user and the ISDN network at  
16 Kbps.  
The D channel is used to manage communication between the equipment and the switch. It is used  
mainly to exchange signal messages with the switch and to set up and release calls. In most cases,  
if there is any incompatibility issue raised, it is the D channel signaling protocol that is causing the  
problem. The Model XM128 modem does not allow the user to use the D channel for sending and  
receiving user data.  
Out-of-Band Signaling  
Some switches transmit all the network signals through the D channel, freeing both B channels to  
be used exclusively for your communication. This arrangement allows a throughput of 128 Kbps  
(64 Kbps per channel). However, not all switches support out-of-band signaling at this time. For  
the switches that do not support out-of-band signaling, network signals are transmitted through B  
channels only, which reduces the bandwidth to 56 Kbps.  
The Model XM128 modem currently supports the following switch types and D channel protocols:  
DSS1  
1TR6  
AT&T 5ESS Custom and National ISDN-1 protocol  
Northern Telecom DMS-100 Custom and National ISDN-1 protocol  
Siemens EWSD National ISDN-1 protocol  
Rate Adaption & B channel protocol  
The Model XM128 modem currently supports the following protocols:  
V.120  
X.75  
V.110  
Asyn-to-sync PPP and PPP/MP  
G-2  
ISDN Reference  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
The B channels are used for carrying user communication information, which can be data,  
voice, or fax. Voice and analog data must be sent on the B channels. Unlike the asynchronous  
communications between most PCs and your Model XM128 modem, the B channel operates  
in synchronous mode. In order to convert the asynchronous communication to synchronous  
communication, it is necessary to use a Rate Adaption Protocol.  
In North America, the V.120 Protocol is the most popular Rate Adaptation Protocol used. The  
V.120 Protocol is an ITU-T protocol that supports synchronous and asynchronous rate adaption  
and provides link-layer error control. NETGEAR also implements V.42bis data compression on  
top of V.120, allowing the user to achieve even higher data communication throughput.  
The Model XM128 modem also supports high-level data link control (HDLC) asynchronous to  
synchronous conversion from Point-to-Point Protocol (PPP). This protocol is very popular for  
Internet access and remote access applications.  
Currently, most of us still use plain old telephone service (POTS) for our regular communication  
needs. The Model XM128 modem provides two POTS ports (PHONE 1 and PHONE 2) for you to  
connect analog devices; this feature lets you continue to use analog communications. You can  
connect phones, fax machines, or analog modems to the PHONE 1 and PHONE 2 ports, while  
using one of the idle B channels (even if the Model XM128 modem is busy doing data  
communications).  
Terminal Adapter or Digital Modem  
A terminal adapter (TA) allows users to send and receive data over the ISDN network. You can  
send and receive both data and voice simultaneously by using both B channels. The PHONE 1 and  
PHONE 2 ports in the Model XM128 modem allow you to connect analog devices to the modem  
to make outgoing calls as well as to receive incoming calls. With its auto-detect feature, the  
Model XM128 modem monitors incoming calls from both analog and digital devices. It monitors  
these calls without user intervention and makes connections accordingly.  
ISDN Basic Rate Interface Points  
In the interest of supporting deregulated Customer Premises Equipment (CPE), the exchange  
Carrier Standard Association in the United States established a basic rate transmission standard for  
CPE. The standards are defined for equipment to connect to different reference points of the ISDN  
link. Some of these reference points are S, T, and U. They have very specific definitions and  
provide standard interfaces for equipment connected to them.  
ISDN Reference  
G-3  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
Not all the interfaces must exist in actual implementations. For example, not all houses are  
equipped with a PBX (NT2). In this case, the U interface is provided by the NT-1 device.  
An ISDN terminal adapter can be constructed with the functionality of an NT-1 device. In this  
case, the terminal adapter connects directly to the U interface. The Model XM128 modem  
connects directly to a U interface without an NT-1 device, which can sometimes be quite  
expensive.  
The Model XM128 modem comes with the following two different types of interfaces:  
An S/T interface  
The Model XM128 modem with an S/T interface is called a Model XM128S modem and  
requires an NT-1 device to be connected between the modem and the ISDN wall connection.  
A U interface for American ISDN  
The Model XM128 modem with a U interface is called a Model XM128U modem and can be  
connected directly to the ISDN jack installed by the telephone company.  
SPID Setup  
Service provider identification (SPID) numbers are needed unless your switch type is AT&T 5ESS  
with Point-to-Point Protocol. The ISDN switches use SPID numbers to represent the subscribed  
network services. Each SPID number corresponds to one terminal end point identifier. Different  
switches might provide different rules for the SPID number format. You should get the SPID  
number from your local telephone company.  
Ordering ISDN Service  
This section provides information about ordering an ISDN line from your telephone company.  
Follow these guidelines and use the information to fill in the appropriate worksheet in this  
appendix:  
Provide the following ISDN codes to the telephone company:  
S
EZ-ISDN-1  
Each code describes a set of capabilities and features that are available in the  
Model XM128 modem. Providing these codes ensures that your ISDN line is installed  
for maximum compatibility.  
G-4  
ISDN Reference  
 
       
Reference Guide for the Model XM128 ISDN Digital Modem  
Make sure the telephone company provides you with:  
The switch type information  
Ask the telephone company representative which switch type is available in your area.  
Select the appropriate worksheet in this appendix and complete the information to use as a  
guide. The three types of worksheets provided are AT& T 5ESS, Northern Telecom  
DMS-100, and Siemens EWSD.  
The switch protocol  
Ask the telephone company representative which switch protocol you will be using to  
communicate with the telephone company switch.  
The SPID numbers  
Determine the number of SPID numbers your configuration requires and request that  
quantity.  
The Directory numbers  
In most cases, you will have two directory numbers. Determine and request the  
appropriate quantity.  
ISDN Reference  
G-5  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
Order Form for AT&T 5ESS Switch (NI-1 ISDN)  
To order ISDN service for the AT&T switch, provide the information on this form to your local  
telephone company by photocopying and faxing this order form.  
First Name: _______________ Last Name: _______________  
Address:___________________________________________  
City:_____________________ State:________ Zip:________  
Telephone (analog): __________________________________  
Refer to Table G-1 for information about your configuring your ISDN line for the AT & T switch.  
Table G-1.  
ISDN line configuration  
Line type  
Standard (2B+D) NI -1 or Custom  
Data line class  
Line code  
Point-to-Point (PPP) or Multipoint  
2B1Q  
Interface type  
B1 service  
B2 service  
Access rate  
U interface with RJ-45 jack  
On demand (DMD)  
On demand (DMD)  
64 Kbps  
Maximum B channels  
2
Circuit-switched voice  
2
Circuit-switched voice channel  
Circuit-switched data  
Any  
2
Circuit-switched data channel  
D channel packet  
Any  
No  
No  
Type A  
Electronic Key Telephone Sets (EKTS)  
Terminal Type  
Information the telephone company must provide:  
Switch Protocol: __ NI-1 __ Point-to-Point __ Multipoint  
Number of SPIDs: __ 0 __ 1 __ 2  
ISDN # 1 _______________ SPID #1 _______________  
ISDN # 2 _______________ SPID #2 _______________  
G-6  
ISDN Reference  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
Order Form for DMS-100 Switch (NI-1 or Custom ISDN)  
To order ISDN service for the DMS-100 switch, provide the information on this form to your local  
telephone company by photocopying and faxing this order form.  
First Name: _______________ Last Name: _______________  
Address:___________________________________________  
City:_____________________ State:________ Zip:________  
Telephone (analog): __________________________________  
Refer to Table G-2 for information about your configuring your ISDN line for the DMS-100  
switch.  
Table G-2.  
ISDN line configuration  
Line type  
Standard (2B+D) NI-1 or custom  
Line code  
2B1Q  
Interface type  
Access rate  
U interface with RJ-45 jack  
64 Kbps  
Directory numbers, logical terminals  
Bearer service  
2
Circuit switch voice and data on any B channel  
Circuit switched service  
Yes  
Packet switched service  
No  
Terminal endpoint identifier (TEI)  
Electronic key telephone sets (EKTS)  
Call appearance handling (CACH)  
Dynamic  
No  
No  
Information the telephone company must provide:  
Switch protocol: __ NI-1 __ Point-to-Point __ Multipoint  
Number of SPIDs: __ 0 __ 1 __ 2  
ISDN # 1 _______________ SPID #1 _______________  
ISDN # 2 _______________ SPID #2 _______________  
ISDN Reference  
G-7  
 
     
Reference Guide for the Model XM128 ISDN Digital Modem  
Order Form for EWSD (NI-1 ISDN)  
To order ISDN service for the EWSD switch, provide the information on this form to your local  
telephone company by photocopying and faxing this order form.  
First Name: _______________ Last Name: _______________  
Address:___________________________________________  
City:_____________________ State:________ Zip:________  
Telephone (analog): __________________________________  
Refer to Table G-3 for information about your configuring your ISDN line for the EWSD switch.  
Table G-3.  
ISDN line configuration  
Line type  
Standard (2B+D) NI-1  
Line code  
2B1Q  
Interface Type  
Access Rate  
U interface with RJ-45 jack  
64 Kbps  
Directory numbers, logical terminals  
Bearer Service  
2
Circuit Switch Voice and Data on any B Channel  
Circuit Switched Service  
Yes  
Packet Switched Service  
No  
Terminal Endpoint Identifier (TEI)  
Electronic Key telephone sets (EKTS)  
Dynamic  
No  
Information the telephone company must provide:  
Switch protocol: __ NI-1 __ Custom  
Number of SPIDs: __ 0 __ 1 __ 2  
ISDN # 1 _______________ SPID #1 _______________  
ISDN # 2 _______________ SPID #2 _______________  
G-8  
ISDN Reference  
 
     
Index  
Numerics  
issuing 4-3  
MSN 4-8  
placing a call 6-3  
result codes 4-4  
types supported 4-3  
V.110 configuration 6-10  
1TR6 communication  
incoming calls 7-8  
outgoing calls 7-5  
placing a call 7-12  
A
ATXn command D-19  
address ambiguity 6-8, 7-9  
address matching 6-8  
ambiguity resolution 7-9  
analog calls 8-1  
B
B channel 10-5  
bundling 5-3  
embedded protocol analyzer 10-5  
protocol 5-1  
ANSI 10-5  
answer modes 5-3  
asynchronous flow control cable F-2  
basic rate interface G-2  
best-effort call answering 6-8  
AT commands  
address ambiguity 6-8  
analog calls 8-2  
auto callback B-4  
basic C-2  
C
cable, asynchronous F-2  
best-effort call answering 6-8  
call, placing 6-3  
capture commands 10-6  
dial strings 6-3  
EAZ 7-6  
EPA 10-7  
European switches 8-2  
extended C-8, C-12  
for analog calls 8-2  
frequently used 8-2  
ISDN numbers, assigning 6-6  
COM LEDs 1-5  
communication speed, setting up 4-4  
configuring  
ISDN line 4-1  
network 4-1  
using a terminal program 4-1  
connect strings D-23  
conventions xviii  
CSD (Circuit Switched Data) 6-4  
customer support iii  
Index  
1
 
 
Reference Guide for the Model XM128 ISDN Digital Modem  
D
I
D channel 10-5, 10-6  
data call indication 7-10  
data compression 6-15  
data over speech channel 6-7  
DCA 5-5  
incoming calls 6-3, 7-10  
installation  
instructions 2-2  
verifying 2-3  
interfaces 1-3  
ISDN  
diagnostic command 10-3  
advanced call control 7-1  
answering a call 7-7  
basic rate interface points G-3  
control of ENDGERATEAUSWAHLZIFFER  
(EAZ) 7-6  
dialing out  
for analog adapter port 1 6-2  
for analog adapter port 2 6-2  
using ISDN mode 6-1  
using speech bearer service 6-2  
LEDs 1-4  
DSS1 (Digital Subscriber Signaling #1)  
incoming calls 7-7  
outgoing calls 7-1  
line configuring 4-1  
numbers, assigning 6-6  
ordering G-4  
placing calls 7-11  
overview G-1  
placing a call 7-11  
port 1-7  
DTE interface, operation modes C-1  
E
L
EAZ 7-6  
LED descriptions 1-4, 2-3  
loopback tests 10-2  
embedded protocol analyzer 10-5, 10-6  
Endpoint Discriminator 5-4  
EPA 10-5  
M
error correction 6-15  
Europe, configuration for 4-7  
modem reset 10-4  
modes, answer 5-3  
MPPP 5-3, 5-4  
MSN 5-3  
answering a call using 6-6  
AT commands 4-8  
F
features 1-1  
flash EPROM, upgrading 9-1  
frequently used AT commands 8-2  
front panel 1-3  
multi-auto answering 6-9, 7-9  
Multilink PPP 5-3, 5-4, 5-5  
N
H
network switches, setting up 4-5  
HDLC 5-1, 5-3  
network, configuring 4-1  
2
Index  
 
Reference Guide for the Model XM128 ISDN Digital Modem  
O
S
out of band signaling G-2  
security  
level 1 B-2  
level 2 B-2  
level 3 B-3  
types and levels B-1  
outgoing calls 6-1  
P
package contents 2-1  
packet length, determining 6-5  
passwords, setting and modifying B-3  
Phone 1 port 1-7  
serial port 1-7  
serial port interface F-1  
simplex mode C-1  
SLIP 5-1  
Phone 2 port 1-7  
Speech bearer 5-3  
point-to-point configuration 7-11  
SPID numbers 4-6, G-4  
port  
S-register  
ISDN 1-7  
Phone 1 1-7  
Phone 2 1-7  
serial 1-7  
descriptions D-4  
extended D-5  
setting D-2  
values 7-2  
viewing D-1  
Power LED 1-4  
Status Register. See S-register  
subaddresses 7-3  
power receptacle 1-7  
PPP 5-1, 5-2, 5-3, 5-4, 5-5  
protocol specifcations 6-9  
PWR LED 1-4  
switches, Northern Telecom 5-2  
T
R
technical specifications A-1  
terminal adapter G-3  
terminal programs 4-2  
troubleshooting 10-1  
rear panel 1-6  
related publications xix  
Remote Access 5-1  
reset modem 10-4  
U
result codes D-21  
RJ-11 connector pin assignments E-3  
RJ-45 connector pin assignments E-1  
RS-232 interface F-1  
RS-232 port 1-6  
United Kingdom, configuration for 4-7  
upgrading with flash EPROM 9-1  
user-to-user information 7-13  
Index  
3
 
Reference Guide for the Model XM128 ISDN Digital Modem  
V
W
V.110  
World Wide Web iv  
call answering 6-10  
making a call 6-10  
V.120  
answering incoming calls 6-12, 6-13  
bundled call 6-13  
configuring 6-12  
dialing out 6-13  
error correction and data compression  
with 6-15  
X
X.75  
Answering a call 6-16  
bundled call 6-17  
ISDN communications for Europe 6-16  
making a call 6-17  
prestored phone numbers 6-18  
making a bundled call with 6-13  
selecting for European ISDN 6-11  
V.42bis data compression 6-18  
4
Index  
 

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