1-2
C
HAPTER
1: I
NTRODUCTION
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.
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 IBM
â
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 Apple
â
Macintosh
â
external digital modem
product.
■
3C877 is the Apple Macintosh external digital modem
product with an internal 14.4 Kbps analog fax modem.
®
3Com
Impact
™
D-Channel
B-1
B-2
Test
Power
3Com Impact
ISDN External
Digital Modem
Internet
or
on-line service
Analog or ISDN line
Analog or ISDN line
Public telephone
network
Corporate
LAN
ISDN line