3Com Network Card DIGITAL MODEM User Manual

3COMâ IMPACTä  
®
ISDN EXTERNAL DIGITAL  
MODEM USER GUIDE  
A member of the 3Com Impact product family  
Part No. 09-0699-002  
Published August 1995  
 
CONTENTS  
ABOUT THIS GUIDE  
Introduction  
i
How to Use This Guide  
Conventions ii  
i
1 INTRODUCTION  
Data Capabilities 1-4  
Voice Capabilities 1-4  
Simultaneous Data and Voice Capabilities 1-4  
Analog Modem Capabilities 1-5  
3Com Impact Digital Modem Package Contents 1-5  
Standard Package Contents 1-5  
Computer System Requirements 1-7  
Apple Macintosh Requirements 1-8  
Cabling Requirements 1-9  
2 INSTALLING AND CONFIGURING  
THE DIGITAL MODEM  
Installing the 3Com Impact Digital Modem 2-3  
Configuring the 3Com Impact Digital Modem 2-6  
Configuration for IBM PC or Compatible Computer 2-7  
Configuration for Apple Macintosh Computer 2-13  
Placing and Receiving Calls 2-15  
Placing ISDN Data Calls 2-15  
Multilink PPP Calls With Dynamic Bandwidth Allocation 2-15  
Placing Analog Modem Calls 2-17  
Using Communications Software to Place Calls 2-17  
Receiving Data Calls 2-17  
 
Placing Calls Using the Phone Out Port 2-18  
Protocol Support 2-19  
Async-Sync PPP Conversion 2-19  
Troubleshooting Tips 3-1  
Downloading Firmware to Your External Digital Modem 3-5  
A AT COMMAND SET OVERVIEW  
AT Command Set for the 3Com Impact  
Digital Modem B-1  
AT Command Set for Internal Analog Fax Modem B-4  
Remote S Registers B-7  
Digital Modem Result Codes B-10  
C TECHNICAL SUPPORT  
On-line Technical Services C-1  
3Com Bulletin Board Service C-1  
World Wide Web Site C-2  
Ask3Com on CompuServe C-2  
3ComFacts Automated Fax Service C-2  
Support from Your Network Supplier C-3  
Support from 3Com C-4  
Returning Products for Repair C-4  
LIMITED WARRANTY  
FCC CLASS B CERTIFICATION STATEMENT  
CANADIAN NOTICE  
 
FIGURES  
1-1 Analog and Digital Network Access with the  
3Com Impact Digital Modem 1-2  
2-1 Back Panel Power Switch and Connectors 2-1  
2-2 Front Panel LED Indicators 2-1  
2-3 Configuration Dialog Box 2-8  
 
TABLES  
1
2
Text Conventions ii  
Notice Icons ii  
1-1 ISDN Ordering Information by Switch Type 1-7  
2-1 Front Panel LED Indicator Definitions 2-2  
B-1 AT Command Set Summary B-1  
B-2 AT Command Set Summary for the Internal Analog Modem B-4  
B-3 Remote S Registers B-7  
B-4 3Com Impact Digital Modem Result Codes B-10  
 
ABOUT THIS GUIDE  
Introduction  
This guide describes how to install, operate, and  
troubleshoot the 3Comâ Impactä ISDN External Digital  
Modem, referred to throughout this guide as the 3Com  
Impact digital modem.  
If the information in the release notes shipped with your  
product differs from the information in this guide, follow the  
release notes. Be sure to read the README.TXT or Read Me  
files on the applicable software utility diskette for the latest  
product information.  
How to Use This Guide  
The following table shows where to find specific information  
in this guide.  
If you are looking for:  
Turn to:  
General information about the 3Com Impact digital modem  
Instructions for installing and operating the digital modem  
Simple digital modem troubleshooting tips  
Chapter 1  
Chapter 2  
Chapter 3  
Appendix A  
Appendix B  
Instructions for using the AT command line set  
Tabular summary of the AT command line set, registers,  
and result codes  
Information about 3Com’s technical support  
Appendix C  
 
     
ii  
ABOUT THIS GUIDE  
Conventions  
Table 1 and Table 2 list text and icon conventions that are  
used throughout this guide:  
Table 1 Text Conventions  
Convention  
Description  
Text represented as This typeface is used to represent displays that appear  
screen  
display  
on your terminal screen, for example:  
NetLogin:  
Text represented as This typeface is used to represent commands that you  
commands  
enter, for example:  
SETDefault !0 -IP NETaddr = 0.0.0.0  
Keys  
When specific keys are referred to in the text, they are called out  
by their labels, such as “the Return key” or “the Escape key,” or  
they may be shown as [Return] or [Esc].  
If two or more keys are to be pressed simultaneously, the keys are  
linked with a plus sign (+), for example:  
Press [Ctrl]+[Alt]+[Del].  
Italics  
Italics are used to denote new terms or emphasis.  
Table 2 Notice Icons  
Icon  
Type  
Description  
Information Note  
Information notes call attention to important features  
or instructions.  
Caution  
Cautions contain directions that you must follow to  
avoid immediate system damage or loss of data.  
Warning  
Warnings contain directions that you must follow for  
your personal safety. Follow all instructions carefully.  
 
         
INTRODUCTION  
1
The Integrated Services Digital Network (ISDN) is a digital  
communications standard for supporting voice, data, and  
video applications through conventional telephone wires.  
Specifically, ISDN is a method of connecting to the public  
telephone network using digital technology. ISDN uses the  
existing copper wire and public telephone network  
infrastructure. All existing voice services provided by the  
telephone companies are accessible using ISDN, and for the  
first time, high-speed dial-up data can be provided  
cost-effectively to the mass market.  
Two electrical interfaces are defined as part of ISDN. The first  
and less expensive is Basic Rate ISDN, or 2B+D. A Basic Rate  
Interface (BRI) has two 56 or 64 Kbps (kilobits per second)  
B (Bearer) channels for user data, and one 16 Kbps signaling  
D (Data) channel, used for packet communications with the  
public network and providing status and control information.  
In most regions, the ISDN BRI is priced at 1.5 to 1.8 times the  
monthly cost of an analog POTS (plain old telephone service)  
telephone line. You may dial voice or data connections on  
either or both of the B channels simultaneously. Calls placed  
from an ISDN line may connect to remote sites that have  
analog POTS, Switched 56, ISDN BRI, or T1 telephone lines.  
There is full compatibility with existing services, and no need  
for ISDN BRI on both ends.  
The other electrical interface, which is somewhat more  
expensive, is the ISDN Primary Rate Interface (PRI). PRI is  
based on the more expensive and higher-speed T1 networks  
that are typically deployed at larger sites. PRI consists of 23  
B channels and one 64 Kbps D channel, providing large  
businesses with a greater degree of flexibility.  
 
     
1-2  
CHAPTER 1: INTRODUCTION  
The 3Com Impact ISDN External Digital Modem (referred to as  
the 3Com Impact digital modem throughout this guide) is an  
external, stand-alone ISDN Basic Rate digital modem for  
connection with digital telephone services from local telephone  
companies in North America. It is designed for users who  
require high-speed access to the Internet, on-line information  
services, or their corporate local area network (LAN). A typical  
3Com Impact digital modem application is shown in Figure 1-1.  
3Com Impact  
ISDN External  
Digital Modem  
Internet  
D-Channel  
B-1  
Power  
Test  
B-2  
or  
pact  
Im  
3
Com  
®
on-line service  
ISDN line  
Public telephone  
network  
Analog or ISDN line  
Analog or ISDN line  
Corporate  
LAN  
Figure 1-1 Analog and Digital Network Access with the 3Com Impact  
Digital Modem  
Four models of the 3Com Impact digital modem are sold in  
the U.S. and Canada:  
3C871 is the IBMâ or IBM-compatible PC external digital  
modem product.  
3C872 is the IBM or IBM-compatible PC external digital  
modem product with an internal 14.4 Kbps analog fax  
modem.  
3C876 is the Appleâ Macintoshâ external digital modem  
product.  
3C877 is the Apple Macintosh external digital modem  
product with an internal 14.4 Kbps analog fax modem.  
 
   
3Com Impact Digital Modem Features  
1-3  
The 3Com Impact digital modem can be connected to any  
compatible ULâ-listed IBM ATâ-compatible or Apple Macintosh  
personal computer that includes instructions for the installation  
of hardware and software options to serial ports.  
3Com Impact Digital Modem Features  
The 3Com Impact digital modem provides the following:  
A complete digital network termination (Basic Rate ISDN NT1).  
Full ISDN signaling support of National ISDN and  
pre-National ISDN service offerings.  
An asynchronous RS-232-C data port for connectivity to IBM  
or compatible PC and Apple Macintosh serial ports at rates of  
up to 115.2 Kbps.  
AT command set dialing.  
Interoperability support through standard protocols like  
Point-to-Point Protocol (PPP) and V.120. (V.120 is a rate  
adaption scheme to convert transmission rates from a range  
of 50 bps to 19.2 Kbps to the B channel 64 Kbps rate.)  
Multilink PPP support, which allows the two B channels to be  
virtually linked, thereby allowing a maximum digital  
connection of 128 Kbps.  
Dynamic bandwidth allocation (DBA), which allows you to  
place a voice call while a Multilink PPP call is active.  
Internal 14.4 Kbps analog fax modem (V.32bis compliant) for  
connection to non-ISDN fax machines and modems (applies  
to 3C872 and 3C877 models only).  
An analog voice port for attaching analog telephones,  
answering devices, and fax machines to the ISDN line.  
A graphical user interface for digital modem configuration.  
A comprehensive diagnostic test and LED status display.  
One-year limited warranty within the “Other Hardware  
Products” category of the 3Com Limited Warranty at the end  
of this guide.  
 
 
1-4  
CHAPTER 1: INTRODUCTION  
Data Capabilities  
The 3Com Impact digital modem allows transmission of  
asynchronous data at speeds of up to 115.2 Kbps over digital  
ISDN connections with the highest reliability and error-free  
performance possible. With Multilink PPP, a digital connection  
of up to 128 Kbps can be established by aggregating the two  
56 Kbps or 64 Kbps ISDN B channels. Note that the COM port  
speed of your PC limits the maximum data transmission rate to  
no more than 115.2 Kbps.  
ISDN technology reduces call setup times by more than 50%  
compared to V. fast/V.34 analog modem setup times,  
reducing the time it takes to establish a connection to under  
three seconds.  
This high-speed performance allows you to do the following:  
Dial up the Internet at high data rates  
Access your office’s LAN  
Access and download graphics, software, and data files more  
quickly  
Voice Capabilities  
The 3Com Impact digital modem’s Phone Out port allows the  
use of existing analog telephone equipment (touch-tone  
telephones, cordless telephones, and fax and answering  
machines) to place and receive calls over the ISDN line. When  
you connect to another ISDN line, setup times are reduced,  
and voice quality is excellent.  
Simultaneous Data and Voice Capabilities  
The 3Com Impact digital modem quickly processes data and  
voice calls simultaneously. For example, you can send a fax or  
place a voice telephone call while maintaining a high-speed  
connection to the office LAN; you can also receive a voice  
telephone call while you are connected to the Internet.  
 
     
3Com Impact Digital Modem Package Contents  
1-5  
Analog Modem Capabilities  
The 3Com Impact digital modem (models 3C872 and 3C877)  
includes an integrated V.32bis analog modem for data or fax  
transmissions of up to 14.4 Kbps over the ISDN line. V.42bis  
data compression boosts analog modem throughput to up  
to 57.6 Kbps.  
3Com Impact Digital Modem Package Contents  
3Com Impact digital modems are available in Macintosh and PC  
versions, with or without a built-in V.32bis analog fax modem.  
Standard Package Contents  
The following list describes the package contents common  
to models 3C871, 3C872, 3C876, and 3C877. Refer to the  
section “Additional Contents” for any additional items that  
are specific to a particular model.  
One 3Com Impact ISDN digital modem  
One power cable with an ac wall transformer  
One serial cable  
One RJ -45/RJ -11 ISDN telephone cable  
One 3.5" installation diskette  
3Com Impact ISDN External Digital Modem User Guide  
3Com Impact ISDN External Digital Modem Quick Start  
Instructions  
Additional Contents  
Model 3C871  
One copy of TurboComä Windowsä software  
One DB-9-to-DB-25 serial connection adapter  
 
         
1-6  
CHAPTER 1: INTRODUCTION  
Model 3C872  
One copy of TurboCom Windows software  
One copy of Delrinaâ WinCommä Lite and WinFaxâ Lite  
communications software  
One DB-9-to-DB-25 serial connection adapter  
ISDN Digital Line Configuration Requirements  
The 3Com Impact digital modem requires an ISDN digital  
telephone line that is properly configured for use with the  
digital modem.  
3Com has determined the optimal ISDN line configurations  
for the 3Com Impact digital modem and has provided that  
configuration data to many telephone companies.  
To simplify the ordering process for an ISDN digital line, use  
the following simplified ISDN ordering code:  
3ComA * J6  
If your digital modem has an internal analog fax modem  
(Models 3C872 and 3C877), then two directory numbers  
(telephone numbers) will be required to allow a voice call  
and a fax modem call to occur at the same time. When you  
tell the telephone company the ISDN ordering code  
(3ComA * J6), let the representative know that you will need  
two directory numbers.  
If your telephone company does not support simplified ISDN  
ordering codes, refer to Table 1-1 for ISDN ordering  
information.  
Present this ordering information to the ISDN line installer or  
telephone company service representative in your area. Also,  
make sure that your local telephone company installer  
provides an RJ-11 or RJ-45 connector for your ISDN line.  
 
 
Computer System Requirements  
1-7  
Table 1-1 ISDN Ordering Information by Switch Type  
ISDN Switch Type  
Northern  
Telecomâ  
DMS100  
National  
ISDN-1  
Siemensâ  
EWSD  
National  
ISDN-1  
ISDN Line  
AT&T 5ESS  
National  
ISDN-1  
Configuration AT&Tâ 5ESS  
Parameter  
Custom  
Line Code  
2B1Q (no NT1  
required)  
2B1Q (no NT1  
required)  
2B1Q (no NT1  
required)  
2B1Q (no NT1  
required)  
Directory  
Numbers  
1*  
1*  
2
1*  
Channels  
2B alternate  
2B alternate  
2B alternate  
2B alternate  
circuit-switched circuit-switched circuit-switched circuit-switched  
data and voice data and voice data and voice data and voice  
Terminal Type  
TEI  
A with  
Point-to-Point  
A with  
Point-to-Point  
Functional PVC 2 Functional  
Dynamic  
Idle  
Dynamic  
Idle  
Dynamic  
Dynamic  
Call  
Appearances  
Supplemental  
Voice Features  
None  
None  
None  
None  
EKTS Features  
No  
No  
No  
No  
No  
No  
No  
No  
D Channel  
Packet  
B Channel  
Packet  
No  
No  
No  
No  
* Two directory numbers are required for Models 3C872 and 3C877. This allows a voice call and a  
call using the internal analog fax modem to occur at the same time.  
Computer System Requirements  
Connect the model 3C871 or 3C872 3Com Impact digital  
modem to an IBM-compatible computer. Connect the model  
3C876 or 3C877 3Com Impact digital modem to an Apple  
Macintosh computer. Connect the digital modem to a  
computer that meets UL standards in the United States or is  
certified to CSA standards in Canada.  
 
       
1-8  
CHAPTER 1: INTRODUCTION  
IBM PC or Compatible Requirements  
An IBM-compatible PC must have the following:  
A 386, 486, or Pentiumâ processor  
An available serial communications port  
For sustained performance at higher data rates (57.6 Kbps  
and 115.2 Kbps), it is recommended that your IBM or IBM-  
compatible PC serial COM port be equipped with a 16C550  
UART (universal asynchronous receiver/transmitter). To  
determine what UART is installed in your PC, run the  
Microsoftâ Diagnostic Program (msd) from the DOS prompt.  
In addition, for reliable high-speed serial port performance in  
the Microsoft Windows environment, a TurboComä driver for  
Windows, which replaces the standard Microsoft Windows  
COM driver, is included with the 3Com Impact digital modem.  
MS-DOSâ or IBM PC DOS 3.1 or later operating system  
640 Kilobytes of conventional memory  
Microsoft Windows 3.1 or later (optional)  
A hard disk drive with 1 MB of free space  
Apple Macintosh Requirements  
An Apple Macintosh computer must be a Macintosh Plus or  
later model. It must also have the following:  
An available serial communications port  
The highest possible serial port data rate with most  
Macintosh computers is 57.6 Kbps. Some later Macintosh  
models (AV and Power Macintoshä) have data rates of up to  
115.2 Kbps. 3Com recommends that you use the 8-pin serial  
communications port on your Macintosh.  
System 7 or later operating system  
A hard disk drive with 1 MB of free space  
 
   
Cabling Requirements  
1-9  
Cabling Requirements  
Cables to connect the 3Com Impact digital modem to your  
computer are provided. For IBM or IBM-compatible PCs with  
a 25-pin serial port, a DB-9–to–DB-25 connection adapter is  
included with the digital modem.  
The asynchronous RS-232-C port on the digital modem,  
labeled Computer, is a standard DB-9 female connector. The  
digital modem asynchronous port pin assignments, shown in  
Table 1-2, conform to standard definitions for data  
communications equipment (DCE).  
Table 1-2 Pin Descriptions  
Pin #  
Pin Name  
Signal Direction  
From digital modem  
From digital modem  
To digital modem  
To digital modem  
1
2
3
4
Carrier Detect (DCD)  
Receive Data (RD)  
Transmit Data (TD)  
Data Terminal Ready  
(DTR)  
5
6
7
8
9
Signal Ground (GND)  
Data Set Ready (DSR)  
Request to Send (RTS)  
Clear to Send (CTS)  
Ring Indicator (RI)  
From digital modem  
To digital modem  
From digital modem  
From digital modem  
 
     
INSTALLING AND  
CONFIGURING  
THE DIGITAL MODEM  
2
3Com Impact digital modem. In combination with the  
instructions given in this chapter, follow the instructions  
given in the appropriate PC or Macintosh computer user  
guide. Refer to Figure 2-1 and Figure 2-2, showing the digital  
modem back and front panels, during installation and  
configuration. If you encounter difficulties after installation,  
refer to Chapter 3,“Troubleshooting.”  
Wall  
Power  
12V AC  
RS232D  
RS232D  
ISDN BRI-U ONLY  
Figure 2-1 Back Panel Power Switch and Connectors  
The LED status display, shown in Figure 2-2, consists of five  
front panel LEDs that are described in Table 2-1.  
®
3ComImpact  
Figure 2-2 Front Panel LED Indicators  
 
             
2-2  
CHAPTER 2: INSTALLING AND CONFIGURING THE DIGITAL MODEM  
Table 2-1 Front Panel LED Indicator Definitions  
LED  
Color Description  
Power  
Yellow Power Indicator. Lit when power is on and remains lit as long  
as power is available from the ac wall transformer plugged into  
the electrical outlet.  
Test  
Yellow Self-Test/Status. Flashes when the digital modem is  
executing its power-up self-test or a user-initiated reset. If the  
results of the self-test or reset are normal, the LED goes off. If  
the result of the self-test is abnormal and a fault is detected,  
the LED remains lit but does not flash.  
D-Channel  
Yellow D Channel/Status. Provides a quick indication of the ISDN  
physical network interface and D channel status. If the physical  
ISDN interface is not synchronized or is disconnected, this LED  
remains lit.  
If the physical interface establishes synchronization and the  
ISDN D channel signaling procedures are not properly  
established, the LED flashes.  
Once the physical and D channel signaling are synchronized,  
the LED goes off.  
If any physical loss of framing occurs, the LED lights; if there is  
a loss of D channel signaling, the LED flashes.  
B-1  
B-2  
Yellow B-1 Channel Indicator. Indicates the activity state of the B-1  
or  
channel of the ISDN interface. Green indicates a  
green circuit-switched data call. Yellow indicates a circuit-switched  
voice call. If a call is in a dialing state, the LED flashes. When a  
call enters the active state, the appropriate LED color stays lit.  
When the call is disconnected, the LED goes off.  
Yellow B-2 Channel Indicator. Indicates the activity state of the B-2  
or  
channel of the ISDN interface. Green indicates a  
green circuit-switched data call. Yellow indicates a circuit-switched  
voice call. If a call is in a dialing state, the LED flashes. When a  
call enters the active state, the appropriate LED color stays lit.  
When the call is disconnected, the LED goes off.  
 
   
Installing the 3Com Impact Digital Modem  
2-3  
Installing the 3Com Impact Digital Modem  
This installation procedure assumes that you are familiar  
with IBM and IBM-compatible or Apple Macintosh  
computers. If you are not, refer to the user guide that  
accompanied your computer for instructions on hardware  
installation and operating system commands.  
Installing the Digital Modem in an IBM-compatible PC  
To install the 3Com Impact digital modem model 3C870 or  
3C872 in an IBM or IBM-compatible computer:  
1
2
Turn off the computer.  
Ensure that the 3Com Impact digital modem power switch  
is in the Off position.  
3
Insert the 9-pin male end of the 3Com Impact digital  
modem-to-PC serial signal cable into the connector  
labeled Computer on the digital modem’s back panel and  
tighten the connector screws.  
4
Connect the other end of the 3Com Impact digital  
modem-to-PC serial signal cable to a serial  
communications (COM) port on the back of your PC and  
tighten the connector screws.  
Most COM port connectors are labeled COM, SERIAL, or  
RS-232-C. On an IBM AT PC and most laptops or notebooks,  
connect the cable to a 9-pin COM port connector.  
5
6
Connect the 3Com Impact digital modem power cable to the  
connector marked 12V AC on the back panel of the digital  
modem.  
See Figure 2-1 for the location of the 12V AC connector on  
the digital modem’s back panel.  
Plug the transformer end of the power cable into a  
standard 117V ac wall outlet.  
 
   
2-4  
CHAPTER 2: INSTALLING AND CONFIGURING THE DIGITAL MODEM  
7
8
Connect the RJ-45 (8-pin) connector end of the  
RJ-45/RJ-11 ISDN cable to the RJ-45 connector labeled  
Wall on the digital modem’s back panel.  
See Figure 2-1 for the location of the RJ-45 connector on the  
digital modem’s back panel.  
Connect the RJ-11 (6-pin) connector end of the  
RJ-45/RJ-11 ISDN cable to the RJ-11 ISDN wall jack.  
CAUTION:The 3Com Impact digital modem is designed  
to operate with Basic Rate ISDN 2B1Q U Interface network  
terminations. An internal Network Termination device  
3Com Impact digital modem ISDN port to a standard  
analog telephone jack or to an external NT1 device. Make  
sure that it is connected to the ISDN jack.  
9
Turn on the 3Com Impact digital modem by toggling the  
power switch on the back panel to the On position.  
See Figure 2-1 for the location of the power switch on the  
panel (see Figure 2-2) flash momentarily as the unit  
undergoes a power-up self-test diagnostic.  
10 Turn on the computer’s power switch.  
11 Go to the section “Configuration for IBM PC or  
Compatible Computer” later in this chapter to configure  
the 3Com Impact digital modem.  
Installing the Digital Modem in an Apple Macintosh  
Computer  
To install the 3Com Impact digital modem model 3C875 or  
3C877 in an Apple Macintosh computer:  
1
2
Turn off the computer.  
Ensure that the 3Com Impact digital modem power switch  
is in the Off position.  
 
 
Installing the 3Com Impact Digital Modem  
2-5  
3
4
Insert the 9-pin male end of the 3Com Impact digital  
modem-to-Macintosh serial signal cable into the  
connector labeled Computer on the digital modem’s back  
panel and tighten the connector screws.  
Connect the other end of the 3Com Impact digital  
modem-to-Macintosh serial signal cable to the serial  
communications port on the back of the Macintosh.  
The serial communications port is the mini-DIN, 8-pin serial  
port connector, indicated on the Macintosh connector panel  
by the telephone handset imprint.  
5
Connect the 3Com Impact digital modem power cable to  
the connector marked 12V AC on the back panel of the  
digital modem.  
See Figure 2-1 for the location of the 12V AC connector on  
the digital modem’s back panel.  
6
7
Plug the transformer end of the power cable into a  
standard 117V ac wall outlet.  
Connect the RJ-45 (8-pin) connector end of the  
RJ-45/RJ-11 ISDN cable to the RJ-45 connector labeled  
Wall on the digital modem’s back panel.  
See Figure 2-1 for the location of the RJ-45 connector on the  
digital modem’s back panel.  
8
Connect the RJ-11 (6-pin) connector end of the  
RJ-45/RJ-11 ISDN cable to the RJ-11 ISDN wall jack.  
CAUTION:The 3Com Impact digital modem is designed  
to operate with Basic Rate ISDN 2B1Q U Interface network  
terminations. An internal Network Termination device  
(NT1) is built into the digital modem. Do not connect the  
3Com Impact digital modem ISDN port to a standard  
analog telephone jack or to an external NT1 device. Make  
sure that it is connected to the ISDN jack.  
 
2-6  
CHAPTER 2: INSTALLING AND CONFIGURING THE DIGITAL MODEM  
9
Turn on the 3Com Impact digital modem by toggling the  
power switch on the back panel to the On position.  
See Figure 2-1 for the location of the power switch on the  
panel (see Figure 2-2) flash momentarily as the unit  
undergoes a power-up self-test diagnostic.  
10 Turn on the computer’s power switch and restart.  
11 Go to the section “Configuration for Apple Macintosh  
Computer” later in this chapter to configure the 3Com  
Impact digital modem.  
Configuring the 3Com Impact Digital Modem  
The 3Com Impact digital modem requires the five essential  
configuration parameters below before it can operate  
properly on an ISDN line. Before configuring the digital  
modem, make sure you have this information readily  
available. These five parameters are provided to you at the  
time of installation of your ISDN line by the telephone  
company installer.  
ISDN Switch Type  
Phone #1 (local directory telephone number)  
SPID #1 (Service Profile Identifier)  
Phone #2 (if required by the telephone company)  
SPID #2 (if required by the telephone company)  
Each of these items is stored in special S registers within the  
digital modem. These S registers are set by issuing ATSxx=  
commands to the digital modem. The Impact digital modem  
software will automatically issue the AT commands to set the  
S registers as part of the configuration process.  
The following three sections describe how to configure the  
3Com Impact digital modem using the Windows, DOS, or  
Macintosh operating systems, respectively.  
 
   
Configuring the 3Com Impact Digital Modem  
2-7  
After you configure the digital modem and verify that it is  
working properly, you should install the TurboCom software.  
Refer to the installation instructions that came with the  
TurboCom software. This software is required only for  
IBM PC or compatible computers running Windows 3.X.  
Configuration for IBM PC or Compatible Computer  
You can configure the 3Com Impact external digital modem  
for an IBM PC or compatible using either the Windows-based  
installation program or the MS-DOSâ–based installation program.  
Configuration Using Windows  
To configure the digital modem for an IBM PC or compatible  
computer using Windows:  
1
2
Insert the 3Com Impact DOS & Windows Installation  
Diagnostic Utilities diskette into an available diskette drive.  
Select Run from the File menu. In the Run dialog box, type:  
a:setup  
The check box labeled Run Minimized should be left  
unchecked.  
3
4
Click OK.  
The installation process begins copying the configuration  
program to the hard disk. A message box provides the status  
of the installation and indicates when it is complete.  
Double-click the 3Com Impact icon to access the 3Com  
Impact Configuration dialog box.  
COM1 is the default COM port.  
If the digital modem is connected to COM1, the 3Com  
Impact Configuration dialog box appears, as shown in  
Figure 2-3. Go on to step 5.  
If the digital modem is not connected to COM1, the COM  
Port Provisioning dialog box appears. Choose the  
COM port to which the digital modem is connected.  
 
   
2-8  
CHAPTER 2: INSTALLING AND CONFIGURING THE DIGITAL MODEM  
Click Connect. The 3Com Impact Configuration dialog  
box appears, as shown in Figure 2-3.  
Figure 2-3 Configuration Dialog Box  
A status bar below the Help, Tools, Configure, and Exit  
buttons provides the following ISDN status information:  
Layer 1 status  
Service Profile Identifier (SPID) for telephone numbers 1 and 2  
Terminal Endpoint Identifiers (TEI) 1 and 2 (for information  
purposes only)  
A message bar at the bottom of the dialog box provides help  
for completing the fields. If you click in a field, the message bar  
tells you what information to enter in the field.The message bar  
also provides status information about the digital modem. If the  
digital modem is disconnected from the ISDN telephone line,  
for example, a message indicates this condition.  
The right side of the dialog box shows the digital modem  
software version, along with any installed options (such as  
Multilink PPP or internal analog fax modem).  
 
   
Configuring the 3Com Impact Digital Modem  
2-9  
5
6
7
Select the type of switch, as specified by your telephone  
company, from the Telephone Company Switch  
drop-down list box.  
Click in the Telephone Number field in the Number 1 area  
and enter the telephone number to which your digital  
modem is connected.  
Click in the Service Profile Identifier (SPID) field and enter  
the corresponding SPID for the telephone number you  
entered in the previous step.  
You should have received this SPID from your telephone  
company.  
CAUTION: If the ISDN line has been configured with only one  
telephone number (Point-to-Point), do not include the SPID.  
8
Specify which device should receive the calls coming to  
Telephone Number 1.  
You can select Phone Port or Internal Fax/Modem. If your  
model has the internal analog fax modem installed (Models  
3C872 and 3C877), you can select both.  
If both boxes are checked, the internal analog fax modem  
and the phone will both ring, enabling you to answer using  
either device.  
9
If you have a second telephone number associated with  
your ISDN telephone line (some telephone companies  
require two), enter the number and corresponding SPID in  
the appropriate fields in the Number 2 area.  
10 Specify which device should receive the calls coming to  
Telephone Number 2.  
11 Click the Configure button to download the parameters  
listed in steps 5 through 10 to your digital modem’s  
S registers.  
 
2-10  
CHAPTER 2: INSTALLING AND CONFIGURING THE DIGITAL MODEM  
12 If you have changed the Telephone Company Switch type,  
you must reset the digital modem by turning the power  
switch off and then on.  
13 Verify the configuration.  
Check the status bar (located beneath the Help, Tools,  
Configure, and Exit buttons of the Configuration dialog box)  
to verify correct configuration. If the parameters were  
configured accurately and the digital modem is ready to  
send and receive calls, the status bar fields will appear as  
shown below. Note that the TEI number(s) are not configured  
by the user. The TEI number is provided by the telephone  
company for informational purposes only.  
Layer 1: UP  
SPID 1: Init  
TEI 1: Number from 0 to 127  
SPID 2: Init (if required)  
TEI 2: Number from 0 to 127 (if required)  
14 Click Exit to leave the utility.  
15 Install the TurboCom software.  
Refer to the installation instructions that came with the  
TurboCom software.  
After the TurboCom software is installed, proceed to the  
“Placing and Receiving Calls” section.  
Configuration Using DOS  
To configure the digital modem for an IBM PC or compatible  
computer using DOS:  
1
Create a directory on the hard drive, insert the 3Com  
Impact DOS & Windows Installation Diagnostic Utilities  
diskette into the PC’s diskette drive, and copy all the files  
from the utility diskette to the hard drive.  
 
Configuring the 3Com Impact Digital Modem  
2-11  
Copy the files to a new DOS directory. For example, to create a  
directory dddd on your C drive at the C:\> DOS prompt, type:  
md c:\dddd  
To copy all files from the diskette to a directory \dddd at the  
A:\> DOS prompt, type:  
copy a:*.* c:\dddd  
2
Execute INSTALL from the hard drive.  
At the C:\> DOS prompt, type:  
INSTALL  
The configuration program launches and presents the  
Port Settings screen. To move the cursor around the screen,  
use the [Up Arrow] and [Down Arrow] keys. To select a  
parameter, use the [Space Bar].  
3
Use the [Space Bar] to select the digital modem’s  
COM port and COM port data rate.  
This sets the speed of communication between the  
3Com Impact digital modem and the computer during  
configuration.  
When you select the port, the standard interrupt (IRQ)  
associated with that port is automatically chosen. Select the  
COM port data rate based on the data rate required by the  
destination digital modem and the maximum data rate  
supported by your computer’s COM port.  
The program does not allow you to select a data rate that  
exceeds the speed of your COM port.  
4
5
Press [F10] to connect to the 3Com Impact digital modem  
via the chosen COM port.  
The Configuration screen will appear.  
In the Phone #1 field, enter the telephone number to  
which your digital modem is connected.  
 
2-12  
CHAPTER 2: INSTALLING AND CONFIGURING THE DIGITAL MODEM  
6
Enter the corresponding Service Profile Identifier (SPID) in  
the SPID #1 field for the telephone number you entered in  
the previous step.  
You should have received this SPID from your telephone  
company.  
CAUTION: If the ISDN line has been configured with only one  
telephone number (Point-to-Point), do not include the SPID.  
7
Specify which device should receive the calls coming to  
Phone #1.  
You can select Phone Port or Internal Fax/Modem. If your  
model has the internal analog fax modem (Models 3C872  
and 3C877), you can select both. The Phone Port and Internal  
Fax/Modem check boxes associated with Phone #1 appear  
to the right of Phone #1.  
If both boxes are checked, the internal analog fax modem  
and the phone will both ring, enabling you to answer using  
either device.  
8
9
If you have a second telephone number associated with  
your ISDN telephone line (some telephone companies  
require two), enter the number and corresponding SPID in  
the Phone #2 and SPID #2 fields.  
Specify which device should receive the calls coming to  
Phone #2.  
10 Confirm that the parameters listed in steps 5 through 9  
are correct.  
When these parameters are updated, the information is read  
back to the screen. Check to see that the values have been  
correctly entered.  
11 Press [F10] to update the information in the 3Com Impact  
digital modem.  
 
Configuring the 3Com Impact Digital Modem  
2-13  
12 Reset the digital modem by turning the power switch off  
and then on again.  
If the parameters match those registered at the telephone  
company ISDN switch, the D channel LED lights for a few  
minutes, flashes for several seconds, and then turns off. If the  
LED continues to flash or remains lit, see Chapter 3,  
“Troubleshooting.”  
13 Press [Esc] to return to the main menu.  
Once in the main menu, exit the program.  
14 Go to the section “Placing and Receiving Calls” to place  
your first call.  
Configuration for Apple Macintosh Computer  
To configure the digital modem for an Apple Macintosh  
computer:  
1
2
Insert the 3Com Impact Installer Diagnostic Utilities  
software utility diskette into the diskette drive and copy  
the files by selecting them and dragging them to the  
hard drive icon.  
The Macintosh operating system automatically places the  
files in the appropriate folders.  
Open the 3Com Impact Mac folder and double-click the  
3Com Impact Installer program icon to launch it.  
The utility program presents the Port Settings screen. To  
move the cursor around the screen, use the [Tab] key. Select  
the Modem port and click OK. The Utility dialog box appears.  
3
4
In the Phone Number 1 field, enter the telephone number  
to which your digital modem is connected.  
Enter the corresponding Service Profile Identifier (SPID) in  
the SPID field for the telephone number you entered in  
the previous step.  
 
   
2-14  
CHAPTER 2: INSTALLING AND CONFIGURING THE DIGITAL MODEM  
You should have received this SPID from your telephone  
company.  
CAUTION: If the ISDN line has been configured with only one  
telephone number (Point-to-Point), do not include the SPID.  
5
Specify which device should receive the calls coming to  
Phone Number 1.  
You can select Phone Port or Internal Fax/Modem. If your model  
has the internal analog fax modem (Models 3C872 and 3C877),  
you can select both.  
If both boxes are checked, the internal analog fax modem  
and the phone will both ring, enabling you to answer using  
either device.  
6
If you have a second telephone number associated with  
your ISDN telephone line (some telephone companies  
require two), enter the number and corresponding SPID in  
the Phone Number 2 and SPID Number 2 fields.  
7
8
9
Specify which device should receive the calls coming to  
Phone Number 2.  
Confirm that the parameters listed in steps 3 through 7  
are correct.  
Click the Update Configuration button to update this  
information to the 3Com Impact digital modem.  
10 Reset the digital modem by turning the power switch off  
and then on again.  
If the parameters match those registered at the telephone  
company ISDN switch, the D channel LED lights for a few  
minutes, flashes for several seconds, and then turns off. If the  
LED continues to flash or remains lit, see Chapter 3,  
“Troubleshooting.”  
11 Go to the section “Placing and Receiving Calls” to place  
your first call.  
 
Placing and Receiving Calls  
2-15  
Placing and Receiving Calls  
This section illustrates how to place and receive a variety of  
calls with your 3Com Impact digital modem. The digital  
modem uses AT commands and S registers for call  
management. See Appendix A, “AT Command Set  
Overview,” for instructions on use of the AT command set,  
and Appendix B, “AT Commands, Registers, and Result  
Codes,” for a tabular summary of the AT command lines.  
Placing ISDN Data Calls  
When you need to place a call from your PC or Macintosh,  
the 3Com Impact digital modem recognizes the AT  
command ATD to dial a digital ISDN data call. Depending on  
the setting of register S60, 56 Kbps (default) or 64 Kbps  
B channel transmission speeds are used. Correct examples of  
outgoing circuit-switched digital modem commands with  
dial strings are:  
AT D 1 908 555 7891  
ATD19085555555  
Multilink PPP Calls With Dynamic Bandwidth Allocation  
The 3Com Impact digital modem supports Multilink PPP,  
which allows the two B channels to be virtually linked, thereby  
allowing a maximum digital connection of 128 Kbps. Note  
that both your service and the one that you are dialing into  
must support Multilink PPP, or the virtual linking will not  
occur. Multilink PPP is enabled by default.  
Multilink configuration is facilitated through registers S80,  
S81, S82, and S83. Additionally, dynamic bandwidth  
allocation (DBA) in multilink mode is configured in  
register S70. Register S80 enables (the default) or disables  
Multilink PPP operation.  
 
       
2-16  
CHAPTER 2: INSTALLING AND CONFIGURING THE DIGITAL MODEM  
By default, the 3Com Impact digital modem dials the same  
number for both Multilink PPP channels. If the destination to  
which the digital modem is dialing to establish a second  
Multilink PPP channel requires a different telephone number,  
then this second telephone number is stored in register S81.  
By default, this register is empty. It must be configured  
before you establish each Multilink PPP call. If the  
Multilink PPP destination is a single telephone number for  
both channels, then be sure to clear register S81 by sending  
the command ATS81=<blank> to the digital modem.  
Some Multilink PPP implementations require the use of a  
Multilink PPP option called the Multilink Endpoint Identifier.  
This option is configured in registers S82 and S83.  
Register S82 stores the Multilink Endpoint Identifier Class  
value. Valid classes are listed in Appendix B,“AT Commands,  
Registers, and Result Codes.” Register S83 stores the actual  
Multilink Endpoint Identifier. Note that this option is not  
required in most cases, so these registers typically do not  
have to be changed. If the Multilink Endpoint Identifier is  
required, these values will be provided by your system  
administrator or Internet service provider.  
When dynamic bandwidth allocation is enabled (by default),  
you can place a voice call from a device that is attached to  
the Phone Out port while a Multilink PPP call is active. When  
you lift the telephone handset to place a voice call, the  
digital modem automatically removes one of the Multilink  
PPP connections and uses it for the voice call. Once the voice  
call ends, the digital modem automatically reestablishes that  
channel for Multilink PPP operation.  
There may be cost implications due to the use of two  
B channels for Multilink PPP. Check with your service  
providers, such as the telephone company, Internet access  
provider, or on-line service provider.  
 
Using the Phone Out Port  
2-17  
Placing Analog Modem Calls  
To place a call from your PC or Macintosh using the optional  
V.32bis 14.4 Kbps internal analog fax modem (included with  
models 3C872 and 3C877), use the AT command ATDT (for  
connection to an analog modem using touch-tone dialing) or  
ATDP (for connection to an analog modem using pulse dialing).  
Using Communications Software to Place Calls  
If you are using standard communications software, select a  
Hayes-compatible modem configuration and dial out  
through the 3Com Impact digital modem. Refer to your  
communications software documentation for more details.  
Receiving Data Calls  
Incoming circuit-switched data calls from other  
3Com Impact digital modems or from ISDN devices and  
Sw56 equipment may be received by the digital modem.  
If auto answer is disabled (the default) in register S0, a RING  
message is delivered to the Computer port upon reception of  
an incoming data call to the digital modem. The command AT  
A answers the incoming data call. A CONNECT message is then  
delivered to the Computer port upon successful connection.  
If auto answer is enabled, the call is automatically answered  
and a CONNECT message, indicating the speed of the  
connection, is delivered to the Computer port.  
Using the Phone Out Port  
If you have analog touch-tone telephones, answering  
machines, fax machines, external analog modems, or other  
analog telephone devices, connect them to the 3Com Impact  
digital modem’s RJ-11 modular jack labeled Phone Out on  
the digital modem’s back panel (see Figure 2-1).  
The 3Com Impact digital modem does not support pulse  
dialing (rotary) telephones.  
 
       
2-18  
CHAPTER 2: INSTALLING AND CONFIGURING THE DIGITAL MODEM  
CAUTION: The 3Com Impact digital modem is designed to  
operate with telephones that are compatible with the original  
AT&T 2500 touch-tone telephone standard. 3Com guarantees  
proper operation of up to three compatible touch-tone devices  
on the Phone Out port. The digital modem is designed to  
provide power and ringing for these three devices on up to 100  
feet of AWG 26 or heavier AWG wiring. Although the digital  
modem may function satisfactorily at longer cable distances  
with more than two attached telephones, proper operation at  
longer cable distances is not guaranteed in all situations.  
Specialized telephone equipment, most notably speaker  
phones that draw significantly larger amounts of power, may  
not work at all on the digital modem’s Phone Out port. These  
devices do not conform to the loop current (power)  
specification of the 2500 touch-tone telephone standard, and  
their operation is not guaranteed.  
Placing Calls Using the Phone Out Port  
To place an outgoing call, simply take the telephone  
handset or external fax machine off the hook, wait for a dial  
tone, and dial the destination telephone number.  
Receiving Calls Using the Phone Out Port  
lncoming calls to the telephone number assigned to the  
Phone Out port ring at the Phone Out port unless you are  
busy on another Phone Out port call. If the port is busy, the  
incoming call is automatically disconnected.  
If you have a digital modem with an internal analog fax  
modem (models 3C872 and 3C877) you can have calls routed  
to the internal analog fax modem when the Phone Out port  
is busy. To do this, the digital modem must be configured to  
allow a call to be routed to both the Phone Out port and the  
internal analog fax modem, as described in the section  
“Configuring the 3Com Impact Digital Modem.”  
 
   
Protocol Support  
2-19  
Protocol Support  
Async-Sync PPP Conversion  
One of the most unique and powerful features of the  
3Com Impact digital modem is its ability to convert  
asynchronous Point-to-Point Protocol (PPP) into synchronous  
(HDLC-based) PPP that can be transported in ISDN  
B channels to communications servers and routers that have  
integrated ISDN Basic Rate (BRI), Primary Rate (PRI), or  
T1 access lines.  
A wide variety of software and internetworking products has  
been tested for interoperability with the 3Com Impact  
digital modem’s Async-Sync PPPä conversion software.  
QuickSelect  
The 3Com Impact digital modem supports V.120 and  
Async-Sync PPP conversion. The digital modem uses a  
technique called QuickSelectä so that you do not have to  
manually select the proper protocol for each ISDN call. With  
QuickSelect enabled (the default), the digital modem  
automatically detects and uses the required protocol.  
 
     
TROUBLESHOOTING  
3
This chapter explains how to isolate and solve simple  
problems encountered with the 3Com Impact digital  
modem. Problems may stem from incorrect option settings  
or improper installation. Follow the steps outlined in this  
chapter.  
There are no user-serviceable parts inside your 3Com Impact  
digital modem. Unauthorized opening of the unit will void  
the warranty.  
Troubleshooting Tips  
Before you call 3Com’s technical support organization for  
assistance, check the following:  
1
2
The power supply is connected and the power LED is on.  
Turn the 3Com Impact digital modem power switch off  
and then on again several times and observe the Test LED.  
During power-up self-test, the Test LED flashes.  
If the Test LED flashes and remains on for more than a few  
minutes, there is an internal failure. Notify your reseller that  
the 3Com Impact digital modem has failed the self-test, and  
order a replacement.  
If the LED goes off after the test has been completed, the  
test has been successful.  
3
Verify that the ISDN cable is connected to the digital  
modem, and make sure it is connected to the ISDN wall  
jack.  
 
         
3-2  
CHAPTER 3: TROUBLESHOOTING  
The 3Com Impact digital modem will not operate if  
connected to an analog telephone wall jack. Make sure that  
the digital modem is connected directly into the ISDN wall  
outlet without connection to any intermediate telephone  
equipment (an NT1 device is not required with this digital  
modem).  
4
5
Make sure that the cables provided by 3Com or a 3Com  
authorized reseller are in good condition and show no  
evidence of wear or other physical damage.  
If damage is apparent after close inspection, contact your  
reseller for replacement cables.  
Monitor the status of the D channel LED.  
If you are connected to a live digital ISDN line, the  
D channel LED remains lit for up to a few minutes after  
the self-test but then begins to flash.  
When the D channel LED flashes, it indicates that the  
ISDN signal is present.  
When the D channel LED goes out, it indicates that a  
valid communication channel has been established and  
calls may be attempted by the user.  
If the D channel LED remains lit after more than a few  
minutes, it is likely that there is a poor physical  
connection to the local telephone company.  
This fault can be caused by a damaged cable, a broken  
wire, a damaged connector, a nonstandard U interface  
(proprietary AMI line coding), or a problem within the  
telephone company network. If the telephone wires at  
your site appear to be satisfactory, call your local  
telephone company for repair of telephone company  
equipment and troubleshooting assistance.  
If the D channel LED flashes for more than a few minutes  
without going out, there is probably a mismatch between  
the settings of the ISDN line and the 3Com Impact digital  
modem configuration.  
 
Troubleshooting Tips  
3-3  
Check the Service Profile Identifier (SPID) entry and the  
Phone# information in the digital modem software  
configuration utility.  
If you have verified once again that your SPID and Phone#  
parameters are entered properly and the D channel LED  
continues to flash without going out, call your telephone  
company, verify that you have been given the correct SPID  
and Phone# information, and ask whether the ISDN line is  
Point-to-Point. If the ISDN line is Point-to-Point, be sure not  
to include the SPID in the configuration.  
Also verify that the telephone company has configured  
the ISDN line properly for the 3Com Impact digital  
modem product (see Table 1-1). If the D channel LED  
does not go out after these verifications, call your reseller  
for line configuration and troubleshooting assistance.  
If the D channel LED goes out, the digital modem is ready  
to place and receive calls.  
If you have a standard analog telephone attached to the  
digital modem’s analog voice port, you can place a voice  
call in the normal fashion. You should have the ability to  
obtain a dial tone, enter digits, and connect to your  
destination. While the voice call is being placed, either  
the B-1 or B-2 channel LEDs will flash yellow. Once the  
voice call is connected and the other party picks up the  
phone, the B-1 or B-2 LEDs that were flashing will now  
remain lit until the call is disconnected.  
If you do not hear a dial tone or cannot establish a call,  
there is most likely a problem with the configuration of  
your ISDN line. Call the telephone company and have it  
verify that your line is configured for circuit-switched  
voice and data service.  
6
Monitor the B-1 and B-2 LEDs.  
Data calls typically involve more interactions than voice calls do.  
Your computer, applications software, or the remote destination  
can prevent establishment of a data call. If you have been able  
to perform all of the above steps, your 3Com Impact digital  
modem is most likely functioning correctly.  
 
3-4  
CHAPTER 3: TROUBLESHOOTING  
If you are unable to establish a data call, carefully monitor the  
B-1 and B-2 LEDs while attempting a data call. The B-1 and  
B-2 LEDs flash green during the data call establishment  
phase. They then remain continuously green once the data  
connection is established.  
If neither of the B-1 or B-2 LEDs flashes green, check to make  
sure that your computer is turned on and operational, that  
your 3Com Impact digital modem cable is properly  
connected and not damaged, and that your application  
software has sent an AT dial command in the proper format.  
Depending upon the location of the destination call you are  
dialing, there may be an incompatible local or toll telephone  
company. Though this is less likely, if you suspect a telephone  
company problem in dialing local or toll data connections,  
contact your local telephone company and have it verify that  
you can dial a data call to the destination telephone number.  
7
If you are able to establish a data call, in which the B-1 or  
B-2 green LED remains lit and you receive a CONNECT  
message at your application software, but you are unable  
to send data, then it is possible that:  
There is a difference in the local and remote B channel  
data rates.  
There is a mismatch in the data communications  
protocols.  
There is an interoperability mismatch between the local  
and remote applications.  
Make sure that the local and remote data applications have  
communication capability and are properly configured.  
Once you have verified that communication capability  
exists, make sure that the B channel call data rate is the  
same as the remote destination call data rate. The default B  
channel data rate used by the digital modem is 56 Kbps.  
Under some circumstances, the data rate may be  
increased to 64 Kbps at both ends of the connection.  
 
Downloading Firmware to Your External Digital Modem  
3-5  
8
If problems persist, refer to Appendix C,“Technical Support.”  
If you have gone through the troubleshooting tips and still  
have not been able to resolve the problem, contact  
technical support. Please have the serial number of your  
3Com Impact digital modem; a list of symptoms, including  
any LED status information; computer display status; and  
relevant information about your application software ready  
when you call.  
Downloading Firmware to Your External Digital  
Modem  
Data communications is an evolving technology. To keep  
pace with this evolution, your digital modem has been  
uniquely designed to be user-upgradable. As recommended  
by 3Com technical support, you may need to download the  
latest firmware to your digital modem. You can use the  
following procedure to download the updated firmware to  
your digital modem.  
For IBM and IBM-Compatible PCs  
This section provides instructions on downloading firmware  
from your PC to your digital modem.  
1
Obtain the latest firmware file from the 3Com FTP site  
ftp.3Com.com.  
2
3
Copy the firmware file to your computer.  
Double-click the 3Com Impact icon to access the  
Configuration dialog box, shown in Figure 2-3.  
4
Click the Tools button.  
The Firmware and Tests buttons appear.  
Use the Tests tool only under the direction of service  
personnel.  
5
Click the Firmware button.  
The Firmware dialog box appears.  
 
 
3-6  
CHAPTER 3: TROUBLESHOOTING  
6
7
Select the firmware file that you copied from 3Com’s  
FTP site and click OK to start the download to the  
3Com Impact digital modem.  
The download will take several minutes.  
Click the Exit button to exit the utility.  
For Macintosh Computers  
This section provides instructions on downloading firmware  
from your Macintosh to your digital modem.  
1
Obtain the latest firmware file from the 3Com FTP site  
ftp.3Com.com.  
2
3
Copy the firmware file to your computer.  
Double-click the 3Com Impact icon to access the  
Utility dialog box.  
Use the Diagnostics button only under the direction of service  
personnel.  
4
5
Click the Update Firmware button.  
Select the firmware file that you copied from 3Com’s  
FTP site and click OK to start the download to the  
3Com Impact digital modem.  
A message box appears and allows you to confirm the  
download. The download will take several minutes.  
6
Click OK.  
 
AT COMMAND SET  
OVERVIEW  
A
Most communications software supports an AT command  
line initialization string. The initialization string sets up the  
3Com Impact digital modem to negotiate and connect  
with a remote modem. Before dialing, the software sends  
the initialization string to the 3Com Impact digital modem.  
The communications software or server stores the  
initialization string and uses it each time it dials. In most  
situations, an initialization string is not necessary with the  
3Com Impact digital modem. If an initialization string is  
required by the communications software or server, use the  
Hayes default initialization string.  
Software that communicates using AT commands  
(ATtention codes) is required to control the 3Com Impact  
digital modem. You can enter these codes manually.  
However, they are often entered automatically by modem  
communications software. For a summary of the AT  
command set, see Appendix B,“AT Commands, Registers, and  
Result Codes.” Below is a sample AT command line:  
AT V1 D 1 800 555 3333 [Enter]  
AT gets the attention of your 3Com Impact digital modem.  
V1 sets the digital modem to verbose mode so that it sends  
its responses in English words instead of numbers.  
D tells the digital modem to dial an ISDN digital connection  
to the phone number that follows.  
[Enter] sends the command line to your 3Com Impact digital  
modem.  
 
       
A-2  
APPENDIX A: AT COMMAND SET OVERVIEW  
Follow these steps to use AT commands:  
1
2
Launch your communications software.  
Be sure your communications software is in terminal mode.  
Be sure the digital modem is in command mode  
(sometimes called local mode or terminal mode) so that it  
interprets your commands.  
When your computer is powered on, the digital modem  
automatically starts in command mode. If you have recently  
used the digital modem to make a call and have not yet  
disconnected, type +++ to switch to command mode.  
3
Type:  
AT <commands> [Enter]  
An AT command line starts with the characters AT. The  
command line can accept up to 40 command characters in  
the line (not including the two AT characters, spaces, or  
[Enter]).  
After completing its tasks, the 3Com Impact digital modem  
sends a message to the screen.  
 
AT COMMANDS,  
REGISTERS, AND RESULT  
CODES  
B
The 3Com Impact ISDN digital modem commands are  
summarized in Table B-1, modem commands for the internal  
analog modem in Table B-1, remote S registers in Table B-3,  
and digital modem result codes in Table B-4.  
AT Command Set for the 3Com Impact  
Digital Modem  
Table B-1 summarizes the AT command set.  
Table B-1 AT Command Set Summary  
Command Function (Example)  
Description  
A
Answer incoming circuit-switched Answers an incoming call.  
digital modem call (AT A)  
&C  
Serial port CD control (AT &C2)  
&C0 forces CD to remain on at all times.  
&C1 forces CD to follow the state of  
carrier from the remote system. CD turns  
on after CONNECT message is sent to  
host (default).  
&C2 forces CD to remain on except  
temporarily after disconnect.  
D
(ATD5551234)  
(ATDT5551234)  
Dials an outgoing 56/64 Kbps  
circuit-switched digital connection.  
DT  
Dials an outgoing analog modem call,  
using the optional V.32bis modem, at a  
maximum modem line speed of  
14.4 Kbps using touch-tone dialing.  
DP  
(ATDP5551234)  
Dials an outgoing analog modem call,  
using the optional V.32bis modem, at a  
maximum modem line speed of  
14.4 Kbps using pulse dialing.  
(continued)  
 
             
B-2  
APPENDIX B: AT COMMANDS, REGISTERS, AND RESULT CODES  
Table B-1 AT Command Set Summary (continued)  
Command Function (Example) Description  
&D  
DTR control (AT &D0)  
&D0 causes digital modem to ignore DTR  
from host.  
&D1 causes digital modem to enter  
command state on detecting on-off  
transition of DTR.  
&D2 causes digital modem to hang up  
current calls upon on-off transition of DTR  
and prepares serial port to accept AT  
command at any speed (default).  
E
AT command echo (AT E0)  
E0 disables the echo of AT commands  
back to the host computer.  
E1 enables the echo of AT commands to  
the host computer (default).  
&F  
H
I
Restore factory defaults (AT &F) Restores all factory default settings.  
Hang up (AT H)  
Hangs up the current connections.  
I0 displays the product and options ID.  
I1 displays the flash memory checksum.  
Identification (AT I0)  
I4 displays the modem product code,  
precomputed checksum, firmware  
revision number, model, interface type,  
country code, and data pump model.  
O
Q
Enter connect state (AT O)  
Result code control (AT Q0)  
Causes the digital modem to go out of  
command mode into on-line mode.  
Q0 enables the output of result codes  
(default).  
Q1 disables the output of result codes.  
Q2 disables the output of result codes in  
answer mode only.  
\Q  
Serial port flow control (AT \Q1) \Q0 disables flow control.  
\Q1 enables bidirectional XON/XOFF  
software flow control.  
\Q3 enables bidirectional RTS/CTS  
hardware flow control (default).  
%R  
Read all S registers (AT %R)  
Provides an output list of all S registers.  
Reads a specific S register setting.  
SN?  
Read configuration register  
(AT S60?)  
SN=  
Write configuration register  
(AT S60=64)  
Writes to a specific S register.  
(continued)  
 
AT Command Set for the 3Com Impact Digital Modem  
B-3  
Table B-1 AT Command Set Summary (continued)  
Command Function (Example) Description  
\S  
Read on-line status: command  
settings (AT \S)  
Reads the status of any parameters that  
have been modified through AT  
commands.  
\T  
Link inactivity timer (AT \T1)  
\T0 disables inactivity timer (default).  
\Tn link inactivity timer in minutes. The  
digital modem automatically disconnects  
the call if no activity is sensed within n  
(n = 0–255) minutes.  
V
Result code format (AT V0)  
V0 enables short form result codes.  
V1 enables long form result codes  
(default).  
&W  
Z
Stores configuration (AT &W)  
Reset (AT Z)  
Stores the configuration of all S registers  
that are not part of the digital modem  
initial configuration set.  
Disconnects all calls in progress and  
performs a complete digital modem  
system reset.  
+++  
$B  
Enter command state  
Causes digital modem to enter the  
command state if it is currently in the  
on-line state.  
Set baud rate (AT $B57600)  
Show version number (AT %V)  
0 — Autobaud (default). Other settings  
are 1200, 2400, 4800, 9600, 19200,  
38400, 57600, and 115200.  
%V  
Displays digital modem firmware version.  
 
B-4  
APPENDIX B: AT COMMANDS, REGISTERS, AND RESULT CODES  
AT Command Set for Internal Analog Fax Modem  
Table B-1 summarizes the AT command set for the internal  
analog modem.  
Table B-2 AT Command Set Summary for the Internal Analog Modem  
Command Function (Example)  
Description  
B
Set 1200 bps (operation= 0)  
Initiates calls using either ITU-T V.220 or  
Bell 212a at 1200 bps.  
0 — V.22  
1 — Bell 212a (default)  
Modem responds with OK  
C1  
F
ATC1  
Select modem modulation mode 0 — Auto detect (default)  
1 — V.21/Bell 103  
3 — V.23  
4 — V.22/Bell 212a  
5 — V.22bis  
6 — V.32bis/V.32 4800 bps  
7 — V.32bis/V.32 7200 bps  
8 — V.32bis/V.32 9600 bps  
9 — V.32bis 12000 bps  
10 — V.32bis 14400 bps  
Modem speaker volume control 0,1 — Low  
2 — Medium (default)  
L
3 — High  
M
Modem speaker operation  
0 — Off  
1 — On during handshaking, off while  
receiving carrier (default)  
2 — On during handshaking, on while  
receiving carrier  
3 — Off while receiving carrier, on  
during answering  
(continued)  
 
   
AT Command Set for Internal Analog Fax Modem  
B-5  
Table B-2 AT Command Set Summary for the Internal Analog Modem (continued)  
Command Function (Example)  
Description  
X
Select the subset of result  
messages that will be used by  
the modem to inform the PC of  
the results of commands  
0 — Basic call progress  
1 — Basic call progress and connection  
rate  
2 — Basic call progress and connection  
rate  
3 — Basic call progress and connection  
rate  
4 — All call progress and connection rate  
0 — Disable  
%E  
%L  
Line quality monitor control  
1 — Enable and retrain  
2 — Enable and fallback/forward  
3 — Enable and auto-retrain but hang up  
immediately if line quality becomes  
insufficient  
Return received line signal level Returns a value that indicates the  
received line signal level  
%Q  
&G  
Report line signal quality  
Generate guard tone  
Reports the line signal quality  
0 — Disable (default)  
1 — Select 1800 Hz guard tone  
&V  
\A  
Display current configuration  
Set MNP max block size  
0 — 64  
1 — 128  
2 — 192  
3 — 256  
\B  
Transmit break to remote  
Sends break to remote modem with a  
length in multiples of 100 ms (n x 100 ms)  
in non-error corrected mode only.  
n = 1–9  
\G  
End-to-end, modem-to-modem 0 — Disable (default)  
flow control  
1 — Enable  
\L  
MNP mode  
0 — Stream (default)  
1 — Block  
(continued)  
 
B-6  
APPENDIX B: AT COMMANDS, REGISTERS, AND RESULT CODES  
Table B-2 AT Command Set Summary for the Internal Analog Modem (continued)  
Command Function (Example)  
\N Set preferred error-correcting  
Description  
0 — Normal speed buffered  
1 — Direct  
mode to be negotiated in a  
subsequent data connection  
2 — Reliable link  
3 — Auto reliable  
4 — Force LAPM  
5 — Force MNP  
-K  
MNP extended services  
Enables/disables conversion of a V.42  
LAPM connection to an MNP 10  
connection.  
0 — Disable  
1 — Enable  
2 — Enable; inhibits MNP extended  
services initiation during V.42 LAPM  
answer mode detection phase  
-Q  
*H  
MNP 10 fallback to 2400 bps  
(V.22bis)/1200 (V.22)  
Enables or disables fallback from MNP 10  
to V.22bis/V.22.  
0 — Disable  
1 — Enable (default)  
Link negotiation speed  
Controls the connection speed for link  
negotiations before upshift occurs  
between two MNP Class 10 modems.  
0 — Highest rate (default)  
1 — 1200 bps  
2 — 4800 bps  
+F  
All fax commands (AT+fax sub- All fax commands  
command)  
 
B-7  
Remote S Registers  
The 3Com Impact digital modem supports the S registers  
listed in Table B-3. All S registers except S0 are the 3Com  
extended registers.  
Table B-3 Remote S Registers  
Registers  
S0  
Descriptions  
Auto Answer  
0 — Disabled (default)  
1 — Enabled  
S50  
ISDN Switch Signaling Type:  
1 — AT&T 5ESS Custom  
3 — NI-1/AT&T 5ESS (default)  
6 — NI-1/NTI DMS 100 or Siemens EWSD  
Phone #1  
S51  
S52  
S53  
S54  
S55  
Phone #1 Service Profile ID (SPID)  
Phone #2 (if required by your carrier)  
Phone #2 Service Profile ID (SPID) (if required by your carrier)  
Terminal Endpoint Identifier 1:  
Stores the first TEI assigned by the switch if a second  
directory number is required by your carrier. A value of 255  
indicates no TEI has been assigned. This field is read-only.  
S56  
S57  
Terminal Endpoint Identifier 2:  
Stores the second TEI assigned by the switch. A value of 255  
indicates no TEI has been assigned. This field is read-only.  
Terminal Initialization State:  
Indicates the status of the first TEI using SPID 1. This field is  
read-only.  
0 — 3Com Impact digital modem has not attempted  
initialization  
1 — 3Com Impact digital modem has initialized successfully  
using SPID 1  
2 — 3Com Impact digital modem has failed initialization  
using SPID 1  
(continued)  
 
     
B-8  
APPENDIX B: AT COMMANDS, REGISTERS, AND RESULT CODES  
Table B-3 Remote S Registers (continued)  
Registers  
Descriptions  
S58  
Terminal Initialization State:  
Indicates the status of the second TEI using SPID 2. This  
information is provided only if your carrier requires a second  
directory number. This field is read-only.  
0 — 3Com Impact digital modem has not attempted  
initialization  
1 — 3Com Impact digital modem has initialized successfully  
using SPID 2  
2 — 3Com Impact digital modem has failed initialization  
using SPID 2  
S59  
U Interface Status:  
This field is read-only.  
0 — U interface is not synchronized with the switch  
1 — U interface is synchronized and ready  
B Channel Data Rate:  
S60  
S61  
56 — 56 Kbps (default)  
64 — 64 Kbps  
Outgoing Call Type:  
0 — Follow dial modifiers (default)  
2 — ISDN  
3 — Internal analog fax modem  
S63 (only for models with Incoming Voice Call Routing (bit map)  
an internal fax modem)  
Bit Position/Feature:  
0 — Phone #1 internal analog fax modem  
1 — Phone #1 Phone Out port  
2 — Phone #2 internal analog fax modem  
3 — Phone #2 Phone Out port  
S65  
Voice Automatic Number Identification:  
Displays the phone number of an incoming voice call. This  
field is read-only.  
S66  
Data Automatic Number Identification:  
Displays the phone number of an incoming data call. This  
field is read-only.  
(continued)  
 
Remote S Registers  
B-9  
Table B-3 Remote S Registers (continued)  
Registers  
Descriptions  
S70  
Dynamic Bandwidth Allocation:  
0 — DBA disabled  
1 — DBA enabled (default)  
B Channel Protocol:  
S71  
0 — QuickSelect (default)  
1 — Async-Sync PPP conversion  
2 — V.120  
S73  
S74  
V.120 Frame Type:  
0 — I frame (default)  
1 — UI frame  
V.120 Maximum Frame Size (range 240–256):  
256 — Maximum frame size of 256 is used (default)  
248 — Maximum frame size of 248 is used (for AdTranâ  
compatibility, use 253)  
S80  
S81  
Multilink PPP:  
0 — Disable  
1 — Enable (default)  
Multilink PPP Directory Number:  
If the destination to which you are dialing a Multilink PPP  
call requires two separate directory numbers, you must  
include the second telephone number of up to 15 digits in  
this S register. If left blank, then the number used to dial the  
first link is used.  
S82  
Multilink PPP Endpoint Identifier Class:  
If required, this information is provided by your Internet  
service provider.  
1 — Locally Assigned Address  
2 — Internet Protocol (IP) Address  
3 — IEEE 802.1 Globally Assigned MAC Address  
4 — PPP Magic-Number Block  
5 — Public Switched Network Directory Number  
Multilink PPP Endpoint Identifier (up to 20 characters)  
S83  
If required, this information is provided by your Internet  
service provider.  
 
B-10  
APPENDIX B: AT COMMANDS, REGISTERS, AND RESULT CODES  
Digital Modem Result Codes  
Table B-4 lists the 3Com Impact digital modem result codes.  
Table B-4 3Com Impact Digital Modem Result Codes  
Short Form Long Form  
Meaning  
0
OK  
Indicates that the most recent command or  
action was successfully completed.  
2
RING  
Indicates that an incoming call is present  
and no AT Answer command is  
outstanding.  
3
NO CARRIER  
Indicates that the most recent call attempts  
did not establish a call or that the physical  
ISDN interface is not operational.  
4
7
ERROR  
BUSY  
Indicates that the most recent command or  
action was not successfully completed.  
Indicates that the most recent call attempt  
did not connect because the remote  
destination was busy.  
5
CONNECT 1200  
CONNECT 2400  
CONNECT 4800  
CONNECT 9600  
CONNECT 14400  
CONNECT 28800  
CONNECT 56000  
CONNECT 64000  
Indicates 1200 bps analog modem  
connection.  
10  
11  
12  
15  
28  
56  
64  
Indicates 2400 bps analog modem  
connection.  
Indicates 4800 bps analog modem  
connection.  
Indicates 9600 bps analog modem  
connection.  
Indicates 14400 bps analog modem  
connection.  
Indicates 28800 bps analog modem  
connection.  
Indicates 56000 bps digital modem  
connection.  
Indicates 64000 bps digital modem  
connection.  
 
     
TECHNICAL SUPPORT  
C
3Com provides easy access to technical support information  
through the variety of services described in this appendix.  
On-line Technical Services  
3Com offers worldwide support, through the following:  
3Com Bulletin Board Service (3ComBBS)  
World Wide Web Site  
Ask3ComSM on CompuServeâ  
3ComFactsSM Automated Fax Service  
3Com Bulletin Board Service  
3ComBBS contains patches, software, and drivers for all 3Com  
products, as well as technical articles. This service is available  
via modem seven days a week, 24 hours a day. To reach the  
service, set your modem to 8 data, no parity, and 1 stop bit.  
Country  
Australia  
France  
Baud Rate  
Telephone Number  
(61) (2) 955 2073  
up to 14400 baud  
up to 14400 baud  
(33) (1) 69 86 69 54  
Germany  
up to 9600 baud  
up to 9600 baud  
(49) (89) 627 32 188  
(49) (89) 627 32 189  
Hong Kong  
Italy (fee required)  
Japan  
up to 14400 baud  
up to 9600 baud  
up to 14400 baud  
up to 14400 baud  
up to 14400 baud  
(852) 537 5601  
(39) (2) 273 00680  
(81) (3) 3345 7266  
(65) 534 5693  
Singapore  
Taiwan  
(886) (2) 377 5838  
(886) (2) 377 5840  
U.K.  
U.S.  
up to 14400 baud  
(44) (144) 227 8278  
up to 14400 baud  
ISDN V.120  
(1) (408) 980 8204  
(1) (408) 654-2703  
 
         
C-2  
APPENDIX C: TECHNICAL SUPPORT  
World Wide Web Site  
Access the latest networking information on 3Com’s World  
Wide Web site by entering our URL into your Internet  
browser:  
This service features news and information about 3Com  
products, customer service and support, 3Com’s latest news  
releases, selected articles from 3TECHâ, 3Com’s  
award-winning technical journal, and more.  
Ask3Com on CompuServe  
Ask3Com is a CompuServe-based service containing patches,  
software, drivers, and technical articles about all 3Com  
products, as well as an interactive forum for technical  
questions. To use Ask3Com, you need a CompuServe account.  
To use Ask3Com:  
1
2
3
Log on to CompuServe.  
Enter go threecom  
Press [Return] to see the Ask3Com main menu.  
3ComFacts Automated Fax Service  
3Com Corporation’s interactive fax service, 3ComFacts,  
provides data sheets, technical articles, diagrams, and  
troubleshooting instructions on 3Com products 24 hours a  
day, seven days a week. Within this service, you may choose  
to access CardFactsâ for adapter information, or NetFactsâ  
for network system product information.  
CardFacts provides adapter installation diagrams,  
configuration drawings, troubleshooting instruction, and  
technical articles.  
Document 9999 provides you with an index of adapter  
documents.  
 
     
Support from Your Network Supplier  
C-3  
NetFacts provides data sheets and technical articles on  
3Com Corporation’s hub, bridge, router, terminal server, and  
software products.  
Document 8888 provides you with an index of system  
product documents.  
Call 3ComFacts using your touch-tone telephone.  
International access numbers are:  
Country  
Hong Kong  
U.K.  
Fax Number  
(852) 537 5610  
(44) (144) 227 8279  
(1) (408) 727 7021  
U.S.  
Local access numbers are available within the following  
countries:  
Country  
Australia  
Denmark  
Finland  
Fax Number  
800 123853  
800 17319  
Country  
Italy  
Fax Number  
1678 99085  
06 0228049  
800 11062  
Netherlands  
Norway  
Sweden  
U.K.  
98 001 4444  
05 90 81 58  
0130 8180 63  
France  
020 792954  
0800 626403  
Germany  
Support from Your Network Supplier  
If additional assistance is required, contact your network  
supplier. Many suppliers are authorized 3Com service  
partners who are qualified to provide a variety of services,  
including network planning, installation, hardware  
maintenance, application training, and support services.  
When you contact your network supplier for assistance, have  
the following information ready:  
Diagnostic error messages  
A list of system hardware and software, including revision levels  
Details about recent configuration changes, if applicable  
If you are unable to contact your network supplier, see the  
following section on how to contact 3Com.  
 
 
C-4  
APPENDIX C: TECHNICAL SUPPORT  
Support from 3Com  
If you are unable to receive support from your network  
supplier, technical support contracts are available from 3Com.  
In the U.S. and Canada, call (800) 876 3266 for customer service.  
Returning Products for Repair  
A product sent directly to 3Com for repair must first be  
assigned a Return Materials Authorization (RMA) number. A  
product sent to 3Com without an RMA number will be  
returned to the sender unopened, at the sender’s expense.  
To obtain an RMA number, call or fax:  
Country  
Telephone Number  
Fax Number  
U.S. and Canada  
(800) 876 3266  
(408) 764 7120  
 
   
LIMITED WARRANTY  
HARDWARE: 3Com warrants its hardware products to be free from defects in workmanship and  
materials, under normal use and service, for the following lengths of time from the date of  
purchase from 3Com or its Authorized Reseller:  
Internetworking products  
One year  
Network adapters  
Lifetime  
Ethernet stackable hubs and unmanaged Ethernet fixed port repeaters  
Lifetime*  
(One year if  
not registered)  
*Power supply and fans in these stackable hubs and unmanaged repeaters One year  
Other hardware products  
Spare parts and spares kits  
One year  
90 days  
If a product does not operate as warranted during the applicable warranty period, 3Com shall, at  
its option and expense, repair the defective product or part, deliver to Customer an equivalent  
product or part to replace the defective item, or refund to Customer the purchase price paid for  
the defective product. All products that are replaced will become the property of 3Com.  
Replacement products may be new or reconditioned. Any replaced or repaired product or part  
has a ninety (90) day warranty or the remainder of the initial warranty period, whichever is longer.  
3Com shall not be responsible for any software, firmware, information, or memory data of  
Customer contained in, stored on, or integrated with any products returned to 3Com pursuant to  
any warranty.  
SOFTWARE: 3Com warrants that the software programs licensed from it will perform in  
substantial conformance to the program specifications therefor for a period of ninety (90) days  
from the date of purchase from 3Com or its Authorized Reseller. 3Com warrants the magnetic  
media containing software against failure during the warranty period. No updates are provided.  
3Com's sole obligation hereunder shall be (at 3Com's discretion) to refund the purchase price  
paid by Customer for any defective software products, or to replace any defective media with  
software which substantially conforms to 3Com's applicable published specifications. Customer  
assumes responsibility for the selection of the appropriate applications program and associated  
reference materials. 3Com makes no warranty that its software products will work in combination  
with any hardware or applications software products provided by third parties, that the operation  
of the software products will be uninterrupted or error free, or that all defects in the software  
products will be corrected. For any third party products listed in the 3Com software product  
documentation or specifications as being compatible, 3Com will make reasonable efforts to  
provide compatibility, except where the non-compatibility is caused by a “bug” or defect in the  
third party's product.  
STANDARD WARRANTY SERVICE: Standard warranty service for hardware products may be  
obtained by delivering the defective product, accompanied by a copy of the dated proof of  
purchase, to 3Com's Corporate Service Center or to an Authorized 3Com Service Center during  
the applicable warranty period. Standard warranty service for software products may be obtained  
by telephoning 3Com's Corporate Service Center or an Authorized 3Com Service Center, within  
the warranty period. Products returned to 3Com's Corporate Service Center must be  
pre-authorized by 3Com with a Return Material Authorization (RMA) number marked on the  
outside of the package, and sent prepaid, insured, and packaged appropriately for safe shipment.  
The repaired or replaced item will be shipped to Customer, at 3Com's expense, not later than  
thirty (30) days after receipt by 3Com.  
 
 
WARRANTIES EXCLUSIVE: IF A 3COM PRODUCT DOES NOT OPERATE AS WARRANTED ABOVE,  
CUSTOMER’S SOLE REMEDY SHALL BE REPAIR, REPLACEMENT, OR REFUND OF THE PURCHASE  
PRICE PAID, AT 3COM’S OPTION. THE FOREGOING WARRANTIES AND REMEDIES ARE EXCLUSIVE  
AND ARE IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, EITHER IN FACT OR BY  
OPERATION OF LAW, STATUTORY OR OTHERWISE, INCLUDING WARRANTIES OF  
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 3COM NEITHER ASSUMES NOR  
AUTHORIZES ANY OTHER PERSON TO ASSUME FOR IT ANY OTHER LIABILITY IN CONNECTION  
WITH THE SALE, INSTALLATION, MAINTENANCE OR USE OF ITS PRODUCTS.  
3COM SHALL NOT BE LIABLE UNDER THIS WARRANTY IF ITS TESTING AND EXAMINATION  
DISCLOSE THAT THE ALLEGED DEFECT IN THE PRODUCT DOES NOT EXIST OR WAS CAUSED BY  
CUSTOMER'S OR ANY THIRD PERSON'S MISUSE, NEGLECT, IMPROPER INSTALLATION OR TESTING,  
UNAUTHORIZED ATTEMPTS TO REPAIR, OR ANY OTHER CAUSE BEYOND THE RANGE OF THE  
INTENDED USE, OR BY ACCIDENT, FIRE, LIGHTNING, OR OTHER HAZARD.  
LIMITATION OF LIABILITY: IN NO EVENT, WHETHER BASED IN CONTRACT OR TORT (INCLUDING  
NEGLIGENCE) SHALL 3COM BE LIABLE FOR INCIDENTAL, CONSEQUENTIAL, INDIRECT, SPECIAL, OR  
PUNITIVE DAMAGES OF ANY KIND, OR FOR LOSS OF REVENUE, LOSS OF BUSINESS, OR OTHER  
FINANCIAL LOSS ARISING OUT OF OR IN CONNECTION WITH THE SALE, INSTALLATION,  
MAINTENANCE, USE, PERFORMANCE, FAILURE, OR INTERRUPTION OF ITS PRODUCTS,EVEN IF  
3COM OR ITS AUTHORIZED RESELLER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH  
DAMAGES.  
Some states do not allow the exclusion of implied warranties or the limitation of incidental or  
consequential damages for consumer products, so the above limitations and exclusions may not  
apply to you. This warranty gives you specific legal rights which may vary from state to state.  
GOVERNING LAW: This Limited Warranty shall be governed by the laws of the state of California.  
3Com Corporation  
5400 Bayfront Plaza  
Santa Clara, CA 95052-8145  
(408) 764-5000  
 
FCC CLASS B CERTIFICATION STATEMENT  
3Com Corporation  
Model Nos: 3C871, 3C872, 3C876, 3C877  
FCC ID: LP2QAREMOTE  
Made in U.S.A.  
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two  
conditions:  
1
2
this device may not cause harmful interference, and  
this device must accept any interference received, including interference that may cause  
undesired operation.  
WARNING: This equipment has been tested and found to comply with the limits for a Class B  
digital device, pursuant to Part 15 of the FCC Rules, and the Canadian Department of  
Communications Equipment Standards entitled, “Digital Apparatus,” ICES-003. These limits are  
designed to provide reasonable protection against harmful interference in a residential  
installation. This equipment generates, uses and can radiate radio frequency energy and, if not  
installed and used in accordance with the instructions, may cause harmful interference to radio  
communications. However, there is no guarantee that interference will not occur in a particular  
installation. If this equipment does cause harmful interference to radio or television reception,  
which can be determined by turning the equipment off and on, the user is encouraged to try to  
correct the interference by one or more of the following measures:  
Reorient or relocate the receiving antenna.  
Increase the separation between the equipment and receiver.  
Connect the equipment into an outlet on a circuit different from the one which the receiver is  
connected to.  
Consult the dealer or an experienced radio/TV technician for help.  
The user may find the following booklet prepared by the Federal Communications Commission  
helpful:  
The Interference Handbook  
This booklet is available from the U.S. Government Printing Office, Washington, D.C. 20402. Stock  
No. 004-000-00345-4.  
NOTE: In order to maintain compliance with the limits of a Class B digital device, 3Com requires  
that you use quality interface cables when connecting to this device. Changes or modifications  
not expressly approved by 3Com could void the user’s authority to operate this equipment. Refer  
to the manual for specifications on cabling types.  
 
 
CANADIAN NOTICE  
The Industry Canada label identifies certified equipment. This certification means that the  
equipment meets certain telecommunications network protective, operation, and safety  
requirements. The Department does not guarantee the equipment will operate to the users’  
satisfaction.  
Before installing this equipment, users should ensure that is permissible to be connected to the  
facilities of the local telecommunications company. The equipment must also be installed using  
an acceptable method of connection. In some cases, the inside wiring associated with a  
single-line individual service may be extended by means of a certified connector assembly. The  
customer should be aware that compliance with the above conditions may not prevent  
degradation of service in some situations.  
Repairs to certified equipment should be made by an authorized Canadian maintenance facility  
designated by the supplier. Any repairs or alterations made by the user to this equipment, or  
equipment malfunctions, may give the telecommunications company cause to request the user  
to disconnect the equipment.  
Users should ensure for their own protection that the electrical ground connections of the power  
utility, telephone lines, and internal metallic water pipe system, if present, are connected  
together. This precaution may be particularly important in rural areas.  
CAUTION: Users should not attempt to make electrical ground connections by  
themselves, but should contact the appropriate inspection authority or an electrician,  
as appropriate.  
 
 

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