Operation Manual

1 Introduction

1.1 What is ISDN?

ISDN is the internationally standardized digital telecom-

munications network. The abbreviation ISDN stands for

Integrated Services Digital Network.

ISDN has three important new features that distinguish it

from conventional communications media:

The first is the integration of services. This means that

all public telecommunications services, such as tele-

phony, data communications, telefax, Teletex or video-

tex, are carried over a single data network. Voice, text,

files and even images can be transmitted over ISDN.

Users can connect several different terminals and use all

available services with one ISDN line. Because the ISDN

subscriber access (called a basic-rate interface, or BRI)

provides two user data channels (B channels), two differ-

ent telecommunications services may be used at the

same time—to receive a fax during a telephone conver-

sation, for example.

The second significant difference is the extraordinary

speed of data transmission in ISDN. Voice and data are

transmitted over both of the BRI’s B channels at the rate

of 2 x 64000 bits per second. Furthermore, the AVM

ISDN-Controller A1 PCMCIA allows ISDN applications

to bundle the two B channels so that throughput is

doubled.

The third important feature of ISDN is the end-to-end

digital transmission of user data: this is the basis for high

transmission quality. Poor connections, noise and inter-

ference, which can cause transmission errors or interrup-

tions in analog networks, are eliminated. Data commu-

nication over ISDN thus is not only faster, but also more

reliable than in analog networks.

Yet it was the personal computer that opened up the full

potential of ISDN: it used to be that each service required

different terminal equipment (a fax machine to send

Excellent line quality

High speed

Integrated services