Integrated Services Digital Network

CHAPTER 1The ISDN objective

DOI: 10.1201/9781003420408-1

1.1 Introduction

The abbreviation for integrated services digital network, ISDN, was introduced in about 1979 to represent the objective towards which digital telecommunications development was tending. The ISDN is defined as follows.

An ISDN is a network, in general evolving from a telephony IDN, that provides end-to-end digital connectivity to support a wide range of services, including voice and non-voice services, to which users have access by a limited set of standard multipurpose user-network interfaces.

CCITT Red Book, Fascicle III.5, p.3.

What is intended by this definition is illustrated in Figure 1.1 in terms of a future residential subscriber to the telephone service who ...