GENERAL ARCHITECTURE

A digital switching system uses the S.P.C. concept and a digitalswitch.
A brief description of the components is given below:


1. Subs. Access Interface:
Analogue or digital subscribers make entry to the exchange at this interface.isdn
protocol translation is done at this interface.no. of digital links are extended
from this interface to switch.


2. PCM Interface:
Any digital exchange can only accept intelligence in pcm decoded form and
hence trunks from other exchange or links from remote subscriber units or other
access systems.


3. Auxilliary Interface:
It is a service peripheral which take care of one or more functions.


4. Controllers:
Various controllers are required to control switching based on the digital
informations received from subscribers or over the trunks.the main control
functions are:
• Call Handler(Register):- this is the control function which processes a call right
from the point of seizure to called party connection.
• Translator:- this control function basically maintains all data base of subs. and
trunks and provides necessary information to call handler enabling the same to
establish connection between calling linkst/s to called link t/s.
• Charger:- computation of charge based on set principles is carried out by this
control function.