3Com EtherLink 3C900B User manual

This manual covers installation and operating instructions for the following 3Com®U.S. Robotics®
modems:
Sportster®Voice 33.6 kbps internal modems
3Com, the 3Com logo, U.S. Robotics, the USRobotics logo, and Sportster are registered
trademarks; Connections, Total Control, Courier, RapidComm, x2, and the x2 logo are trademarks
and Towne Square 2000 is a service mark of 3Com Corporation or its subsidiaries. Windows and
Internet Explorer are registered trademarks of Microsoft Corp. CompuServe is a registered
trademark of CompuServe Inc. America Online is a registered trademark of America Online Inc.
Netscape Navigator is a trademark of Netscape Communications Corp. Any other trademarks, trade
names, or service marks used in this manual are the property of their respective owners.
Copyright © 1997 3Com Corporation or its subsidiaries
7770 North Frontage Road
Skokie, IL 60077-2690
All Rights Reserved

TABLE OF CONTENTS
ii
Before You Begin (Windows 95 Users) 1
Determining Available Resources 1
Determining Your Version of Windows 95 2
Upgrading to x2 Technology 2
Modem Installation with Windows 3.x 3
A Word About COM Ports and IRQs 3
How to Use ComTest to Determine Your Modem’s Settings 5
Testing an Installed Modem 7
What to Do with ComTest’s Recommendation 8
How to Change the Modem’s Settings 10
How to Insert the Modem into the Computer 12
Modem Installation with Windows 95 19
How to Prepare for Plug and Play Installation 19
How to Insert the Modem into the Computer 21
Installing the Modem Drivers 25
Software Installation and Testing 33
Software Installation and Registration Using the Setup Wizard 33
Sending Your First Fax 48

TABLEOFCONTENTS
iii
Installing Other Fax/Data Software 52
Type of Modem 52
Initialization String 52
Flow Control 52
U.S. Robotics Modem Update Wizard 53
Installation 53
Operation 58
Using Modem Station 65
Troubleshooting and Online Help Resources 89
When Plug and Play Fails 95
Online Help Resources 96
Are You Still Having Problems? 100
If You Need to Return the Modem to Us 101
RapidComm Voice Troubleshooting Tips 102
A Note to Users with Older Versions of RapidComm Voice on Their Systems 102
Glossary 103
Technical Quick Reference 113
AT Command Summary 114
S Registers 128
Regulatory Information 138
Manufacturer’s Declaration of Conformity 138

TABLEOFCONTENTS
iv
Caution to the User 139
IC (Canada) 139
UL Listing/CUL Listing 139
Connecting to the Telephone Company 140
Fax Branding 140
Radio and Television Interference 141
For Canadian Modem Users 142
Limited Warranty 145
Index 148

BEFORE YOU BEGIN (WINDOWS®95 USERS)
1
Determining Available
Resources
Your Sportster®Voice modem is a Plug and
Play device. Windows™95 can automatically
identify a Plug and Play device and determine if
your system has the resources necessary to
support the device. However, Plug and Play
will not work if you do not have resources
available or if devices on your system are not
reporting resource usage correctly. Here’s
how you can verify that your system has the
necessary resources before installing the
modem:
1. Click the Windows 95 Start button, point
to Settings, and then click Control Panel.
2. Double-click the System icon.
3. When the “System Properties” screen
appears, click the Device Manager tab.
4. Double-click Computer and the
“Computer Properties” screen appears.
5. Select the option at the top of the screen to
show Interrupt Requests (IRQs).
You will see the IRQs your system is currently
using. If IRQs 3, 4, 5, and 7 are being used,
you need to free an IRQ before you begin
installation. This process involves moving a
device from the IRQ you want to use to a
different (and usually higher) IRQ setting.
Please read the documentation for (or contact
the manufacturer of) the device that is currently
using the IRQ you want to use for your modem
to learn more about how to free the IRQ for
your modem.

BEFOREYOUBEGIN(WINDOWS95 USERS)
2
Determining Your Version of
Windows 95
Follow these steps to determine your version
of Windows 95. This information will be
important during installation.
1. Click the My Computer icon on your
desktop with the right mouse button.
2. Click Properties.
3. In the “System Properties” screen, look at
the system information under the General
tab (circled in the following screen image).
The number following the text “Microsoft
Windows 95” will end with “950”, “950a”,
or “950b”. This indicates your version of
Windows 95. Write this number on the
blank below for later reference. Then click
OK.
Windows 95 version
_________________
Upgrading to x2™Technology
Be sure to read the section titled “U.S.
Robotics Modem Update Wizard” on page 53
for information on upgrading your 33.6
faxmodem to x2™technology, allowing
downloads of up to 56 kbps*.
• IMPORTANT! All x2 products are capable of 56 kbps
downloads; however, due to FCC rules which restrict power
output of the service providers' modems, current download
speeds are limited to 53 kbps. Actual speeds may vary
depending on line conditions. Uploads from end users to service
providers travel at speeds up to 28.8 kbps. An x2 modem, an
analog phone line compatible with x2 technology, and an
Internet Service Provider with x2 service are necessary for these
high-speed downloads. See http://www.3com.com/x2 for details.

MODEM INSTALLATION WITH WINDOWS®3.X
3
You’ll need these items from your
Sportster ®modem box:
modem phone cord
Connections™CD microphone
Plus:
a screwdriver (not included)
AWordaboutCOMPorts
and IRQs
Most computer accessories — a mouse,
sound card, enhanced graphics card, scanner,
etc. — require a special connection through
which they can communicate with the
computer. For some devices, this connection is
called a communications (or COM) port. Most
computers have 1 or 2 COM ports, but they
can have up to 4. Although internal modems
do not connect to COM ports directly, they do
require a COM port setting, which is
determined by the setting on the modem’s
COM jumper pins.
Each COM port uses an interrupt request
(IRQ). An accessory uses an IRQ to get the
attention of your computer’s central

MODEMINSTALLATIONWITHWINDOWS3.X
4
processing unit (CPU) so that the accessory
can perform a task. The computer stops what
it’s doing, depending on the priority of the
request, to help the accessory perform its task.
When two accessories share an IRQ, it’s like
two people asking different questions in unison
to a third person. Just as the person being
asked the two questions cannot understand
either request, a computer can lock up or
otherwise fail to communicate properly with
your modem when there is an IRQ conflict.
DKEY POINT: Accessories cannot
share COM ports and should not share
IRQs. When accessories try to share
settings, they will either not work
properly or not work at all.This section
of the manual will help you understand
the COM/IRQ settings on your new
Sportster modem.
3Com has set your modem to a default Plug
and Play setting geared towards Windows 95
users. In this configuration, the shunts used to
set your modem’s COM port and IRQ settings
are hanging from single jumper pins and will
not affect your modem’s settings. As a
Windows 3.x user, you need to run the
ComTest program (on the Connections CD) to
determine what settings your modem should
use.
NOTE: Some communications
software programs require a particular
setting for your modem (RapidComm,
which shipped with your modem, does
not). If you wish to use a program other
than RapidComm, now is a goodtime to
read that software’s manual to
determine what setting is required.

MODEMINSTALLATIONWITHWINDOWS3.X
5
HowtoUse ComTestto
DetermineYourModem’s
Settings
1. Insert the Connections CD into your CD-
ROM drive.
2. In Windows’ Program Manager, click Run
on the File menu. Type d:\comtest.exe
and press ENTER. This starts ComTest,
the program that determines which COM
ports and IRQs are available for use by
your modem.
3. The screen in the next column appears
when ComTest starts.
• If there is a modem in your computer
which you are replacing with your new
Sportster modem, go to “Testing an
Installed Modem” on page 7 to
determine which COM and IRQ settings
the older modem is using.
• If a modem is not currently installed in
your computer, click Recommend
settings for a new modem.
Then click Next.

MODEMINSTALLATIONWITHWINDOWS3.X
6
4. Click Internal Modem. Then click Next.
5. If you have a free setting, you will see a
screen like this.
COM2/IRQ3 is free in this example.
ComTest might instead recommend
COM1/IRQ4, COM3/IRQ4, or
COM4/IRQ3 for your modem.
Write down the displayed settings. You’ll
need to know these settings later. Click
Next.
If you do not have a free setting, you will
see a screen like this.