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ABOUT B.S.N.L.
It is largest telecommunication company of India and sixth largest in the world.
Currently BSNL has a customer base of 70.3 million.
It has footprints throughout India except for the metropolitan cities of Mumbai and New-Delhi which are managed by MTNL.
Services being provided by B.S.N.L.
Universal Telecom Services
Cellular mobile telephone service
Internet
Intelligent Network(IN)
System of telephony
It deals with the transmission of speech at a distance.
The conversation b/w two speaker takes place due to the sound waves.
Speech of a subscriber is converted into electrical signal by the microphone of the telephone set.
These electrical signal is sent to the desired subscriber through the telephone exchange.
Therefore we can say that exchange is the backbone of telephony communication.
Types of exchange
There are many types of exchange ,that the system are using, these are
1. Manual telephone exchange
2. Auto manual exchange
3. Electronic exchange
Manual telephone exchange
When telephone connections are established with the help of human operators, it is called manual telephony.
It provides telephone facility with low initial cost.
An industry, institution or any other organization may have a small manual exchange.
Auto manual exchange
In this exchange the manual working is converted into automatic working.
It is not possible to convert the entire working of manual into auto manual ,therefore manual exchange are permanently situated near the auto manual exchange
Electronic exchange
In this type of exchange, the interconnection b/w different transmission circuits are done by electronic device.
The advantage of using electronic devices in place of electro-mechanical devices is that no time loss in making a connection and very high speed operation is possible.
The first electronic exchange was installed in Chicago
They give better performance with greater reliability than the existing type of electro-mechanical system.
Evolution of E-10B system
E-10B system is the culmination of a massive R&D effort of digital switching system over many years in the France.
It has evolved from E-10A system.
It has higher call handling/traffic facility.
The first E-10B system was commissioned in June 8 at BREST in FRANCE.
Facilities and services to subscribers
E-10B system offers many “custom calling services” to its subscribers. some popular are as follows:
Short code dialing (abbreviated dialing)
Call waiting indication (camp-on busy)
Automatic alarm call (walk-me service)
Barred access
Last number redial
Charges free lines
E-10B exchange architecture
The E-10B exchange consist of three blocks or subsystem:
Connection unit
Switching network
Control units
Connection units
The connection unit act as a interface b/w external environment and central units.
The units which manage the generation and transmission of digitalized tone and frequency are also categorized as connection units.
Switching network
This is a time division digital switching network.
It has a 3 stage TST architecture.
It employs 4 wire switching for connecting the timeslots of calling and called parties.
Control units
The control units mainly handles telephone call setup.
It also handles supervision, clear down and charging function.
Operation and maintenance centre (OMC)
OMC plays no direct role in call processing so an E-10B will perform switching function even without OMC, but OMC is absolutely essential to facilitate mgmt of E-10B exchange
Main function of OMC are:
Subscriber management
Routing and analysis management
Alarm message processing
Fault tracing
Fault clearing