This document provides an introduction and overview of Integrated Services Digital Network (ISDN). It discusses the evolution of ISDN, starting in the 1960s with PCM digital voice transmission and the formation of CCITT study group D in 1968 to guide ISDN development. The document describes ISDN services and interfaces, including the basic interface with 2B+D channels and primary group interface with 30B+D channels. It provides details on the channel classifications and functions. In closing, it lists the two types of ISDN services - basic rate interface (BRI) and primary rate interface (PRI).

1. Presented by:-
ROSHAN KUMAR(76)

2. Contents:-
 Introduction
 Evolution of ISDN
 Services of ISDN
 Different Interfaces
 Channel classification
 Typical interface structure
 Services used by ISDN

3. Introduction of ISDN
•Known as the Integrated Services Digital Network.
• the ISDN is an integrated network for various types of
communications services handling voice (telephone) and non
voice ( MEANS DATA& IMAGES) informations.

4. Evolution of ISDN:-
 CCITT has been pioneering & guiding the efforts towards
the development of ISDN.
 The process of ISDN started in early 1960s when PCM was
introduced for digital transmission of voice signals.
 But ISDN is introduced in 1980.
 In 1968,CCITT set up a study group called special study
group D which has the responsibility for all ISDN related
activities within the CCITT.

5. Services of Isdn

6. Different Interfaces:-
 The U interface is a two-wire interface between the
exchange and the Network Terminating Unit
 The T interface is a serial interface between a computing
device and a Terminal Adapter, which is the digital
equivalent of a modem.
 The S interface is a four-wire bus that ISDN consumer
devices plug into; the S & T reference points are commonly
implemented as a single interface labeled 'S/T' on an NT1

7. Channel Classification
Channel Type Bit Rate Function
B 64 kbps  To carry user information
 Both Circuit switching mode and packet
switching mode
D
Different
Interfaces.
16 kbps
64 kbps
 To carry signaling & control information for
circuit switching & packet switching. It some
times takes user data packet also.
H 384 kbps to 1920kbps  To carry high-speed packet data such as
facsimile and video

8. Typical Interface Structures
(a) Basic Interface
 This interface is primarily for home users
 The basic interface is set at a transmission speed of 144
kbps. This provides two (2) 64 kbps B-channels(Bearer
channel =64 kb/s) for data (for user information exchange)
and a 16 kbps D-channel (delta chnl)for signaling and
control.

9. Typical Interface Structures
Delta channel (D-channel, 16 kb/s or 64 kb/s) call
signaling information:
 who is calling
 type of call
 calling what number
 The interface is thus referred to as 2B+D.
(2B= 2x64=128, D=16. So 2B+D= 128+16 = 144kbps)

10. Typical Interface Structures
B) Primary Group Interface (for business use) :-
 The primary group is 2.048 Mbps( i.e. One PCM) and the
interface is 30B-channels and single 64 kbps D-channel. D chnl
sometimes carry user data packet but not voice.
 i.e. 30B+D

11. ISDN uses the following two types of
services:-
 Basic Rate Interface (BRI, which offers two B channels and one
D channel (2B+D)
 Primary Rate Interface (PRI), which offers 23 B channels and 1 D
channel in North America and Japan, and 30 B channels and 1 D
channel in Europe and Australia

12. References:-
 www.google.co.in
 www.wikipedia.co.in

13. THANKU