system used in the
switched telephone network
or in large
exchange consists of electronic components
and in older system also human operators that
) telephone subscriber lines
or virtual circuits of digital systems
Typical exchange consist of:
3.Input Output Processor Room
5.Power Plant Room
6.Main Distribution Room
MAIN SECTIONS OF
There are three components of exchange:
The Switching Equipment common to all the
subscriber of the area is located in an
To make possible for a subscriber to
communicate with remaining subscriber
must be connected to the exchange
From OCB through PCM connected to
various sections like WLL,TAX, etc
MAIN DISTRIBUTION FRAME
primary function of MDF is to remove fault. It
also known as
Fault Remove Section.
The telephone numbers are also disconnected in
the MDF because of some specific reason.
ORGANISATION OF THE MDF
On the rack, the tags are situated. One rack is having
eight tags. The counting is done from up (0) to down (7).
Each rack consists of eight tags.
1 tag = 4 core
1 core = 4 bunch
1 bunch = 2 line
The word NE stands for the
‘NUMBER OF EQUIPMENT’.
It is used for testing number and
Wedge is used as a device for checking the ring.
Wedge is placed in jack strips, which is connected to
telephone for checking.
The horizontal side connected to the underground
This cable is having 100 pairs. These pair is
distributed when we allot the telephone number to
Horizontal side is again subdivided in two parts:
with the subscriber line by using 100 pair
One part is connected with the vertical side.
DIFFERENT TYPES OF FAULTS
If two wires are joined together because of
storming air etc.
If two wires get scrape at some places and if
this wire comes in
contact with tree, pillar or any metal objects then this type of
For outdoor connections, jelly filled wires are
used which are affected by natural causes such as rain,
earthquake etc. At such time this fault occurs.
This type of fault occurs due to the
breaking of wires between the vertical side & LEN side.
T he main parts of the Power Room are:
2.UPS(Uninterrupted Power Supply)
3.Charging Discharging Unit
4.Inverter and Convertor Unit
digital switching system which supports a
communication needs like basic telephony,
system has been
developed by CIT ALCATEL of France and
therefore has many similarities to its
10B (also known as OCB
Connection & Control
SMC :Main Control Station
SMA :Auxiliary Equipment Control
SMT :Trunk Control Station
SMX :Matrix Control Station
STS :Synchronization and Time Base
FEATURES OF OCB
is a digital switching
switch. A maximum
of 2048 PCM’s
. It supports both analog and digital
provides telephony, ISDN, Data communication,
value added services.
traffic handling capacity of the system is huge.
OCB FUNCTIONAL UNIT
The OCB283 system is made
up of three independent functional units :
"Subscriber Access Subsystem" which carries
out connection of analogue and digital subscriber
"Connection and Control" which carries out
connections and processing of calls
"Operation and Maintenance" which is
responsible for all functions needed by the
network operating authority.
283 SWITCHING SYSTEM
Any Automatic Switching System comprises
in general of
(a) Switching Network Units
(b) Circuit Connection
(c) Common Control function units
GENERAL ARCHITECTURE OF OCB
283 is the latest Electronics Digital ISDN type
Switching technology being imported in
THIS IS MANUFACTURED BY M/S ALCATEL OF
works on Stored
Exchange can work with all types of Circuit & Subscriber
& also provides for lot of novel facilities to the