ISDN

Intergrated Services Digital Network.This is a system of digital telephony.In ordinary telephone system it uses circuit switching,whereas ISDN can use both circuit as well as packet switched .The available copper cable can be utilised for communication in digital mode.In ordinary pstn connection the no: of terminal equipments connected is less.But in isdn up to 8 equipments can be connected.More than one call can be established simultaneously.The isdn subscribers access the internet at a speed of 64/128kbps .As this is a digital technique the quality of voice or data is extremely good.Call setup time is extremely short in isdn.
Benefits from operators point of view.
Operators can avoid different network for different connections.The existing copper cable is effectevely utilised.
Services offered
Photo telephone :-Called parties can see the pictures .
Desktop video conferencing
Time to send fax is reduced to about 1/4
All other services like call waiting ,call forwarding,call hunting etc the pstn is giving.
More over this the subscriber can see the metering pulses from his own premises.