This document provides a summary of key components and technologies used in BSNL's telecommunications network. It discusses the Public Switched Telephone Network (PSTN) and how it uses circuit switching to establish dedicated connections for calls. It describes the role of telephone exchanges in connecting subscribers and their basic functions. It also outlines other important parts of an exchange like the Main Distribution Frame (MDF), power plant, and leased lines. Additional technologies covered include broadband, Global System for Mobile Communication (GSM), and their components like the base station controller and home location register.

1. JODHPUR INSTITUTE OF ENGINEERING AND
TECHNOLOGY
AN INDUSTRIAL TRANING SEMINAR ON
BSNL
SUBMITTED BY
SURAJ SINGH SOLANKI
Final Year
B.Tech (Electronics and Communication Engineering)

2. CONTENTS
 PUBLIC SWITCH TELEPHONE NETWORK (PSTN)
 TELEPHONE EXCHANGE
 MDF (MAIN DISTRIBUTION FRAME)
 POWER PLANT
 LEASED LINE
 BROADBAND
 GLOBAL SYSTEM FOR MOBILE COMMUNICATION
(GSM)

3. PSTN
 PSTN shorts for Public Switched Telephone Network is a Mesh
Network of lines, trunks and in which telephone exchanges are
interconnected by the transmission circuits.
 It is originally design to optimize the transmission of voice
services.
 It is based on the principle of Circuit Switching.
 In the Circuit Switching, a dedicated communication channel
(circuit) is made between two nodes through the network before
the nodes may communicate. The circuit functions as if the
nodes were physically connected as with an electrical circuit.
 There when a call is made a particular dedicated circuit activates
which eventually deactivates when the call ends.
 Telephone calls transmits as analogue signals across copper
wires.

5. TELEPHONE EXCHANGE
 Equipments which
effects interconnected of
telephones is known as
switching equipment.
 The switching center
which houses the
terminating and
switching equipment is
called telephone
exchange.
 All telephone
subscribers are served
by automatic
exchanges.

6. TELEPHONE EXCHANGE
Switching systems generally
perform three basic functions:
 They transmit signals over the
connection or over separate
channels to convey the identity of
the called address (for example,
the telephone number), and alert
(ring) the called station.
 They establish connections
through a switching network for
conversational use during the
entire call.
 They process the signal
information to control and super
wise the establishment and
disconnection of the switching
network connection.

7. EXCHANGE LAYOUT
 Switch Room.
 Operation and Maintenance room (OMC).
 Power plant room.
 Battery room.
 Main Distribution Frame (MDF) room.
 Leased line room.
 MDF, Power plant and switching room are the three main
components of Exchange room.

8. MDF (MAIN DISTRIBUTION FRAME)
 MDF is a media between
switching network and
subscriber line.
 The whole setup of MDF is
arranged in a room.
 It is a termination point
within the local telephone
exchange.
 Where the exchange
equipment and termination
of local loops are
connected by jumper
wires.
 MDF is also known as

9. FUNCTIONS OF MDF
 Through all copper wires, telephone lines are terminated
and distributed through MDF.
 It is a long steel rack accessible from both sides. Each
jumper is a twisted wire.
 It consist of local & broadband connection frames from
the main exchange area.
 It is used in removing the fault whether it is in internal or
external.

11. POWER PLANT
• It provides 48 volt to
the switch rooms.
• Batteries are charged
by the Power supply, so
that when the electricity
is gone, then the supply
to the switch room is
given by the Batteries.
• Cooling is provided
through Fans & AC.

12. LEASED LINE
 A leased line is a dedicated connection between
two points.
 They can be used for data, or Internet services.
 Generally leased line is purchased by various
banks, organizational institutes etc.
 Customers (like bank, institutes) generally pay a
monthly rate for the service depending on the
distance between the two points.
 The information sent through the leased line
travels along dedicated secure channels,
eliminating the congestion that occurs in shared
networks.

13. BROADBAND
 Broadband is a communication service that provides
the facility to transmit large amount of data at high
speed.
 It is often called high speed internet, because it has
usually a high rate of data transmission.
 Broadband services includes internet access.
 It provides the facility of Video and Audio
Conferencing.
 This is the always-on Internet access service with
speed ranging from 256 kbps to 8 Mbps.
 In India, TRAI (Telephone Regulatory Authority of
India) has defined broadband as any connectivity

14. BROADBAND
Requirement for providing Broad Band
connection
 Personal Computer
 ADSL Modem
 Land Line Connection
 Splitter for separating telephone from
Personal computer.

15. MODEM CONNECTION

16. GLOBAL SYSTEM FOR MOBILE COMMUNICATION
 GSM is a Mobile communication system.
 It includes calling services, SMS(Short message service),
Voice mail, Electronic mail, Incoming and outgoing calls,
Call forwarding, Call hold, Call Waiting.
 High audio quality and reliability for wireless,
uninterrupted phone calls at higher speeds (e.g. from
cars, trains) i.e. high transmission quality.
The frequency allocations in GSM are as follows-
 The band 890-915 MHz has been allocated for the uplink
direction (transmitting from the mobile station to the base
station.)
 The band 935-960 MHz and has been allocated for the
downlink direction (transmitting from the base station to
the mobile station.)

18. MOBILE STATION (MS)
 It consists microphone for
speech encoding.
 It consists Speaker for speech
decoding.
 Short message service
capability.
 Location updates.
 Manage the data of SIM.
 Voice and data
recognition.(Identified by IMEI
(International mobile
equipment identity) Number).

19. MOBILE STATION (MS)
 Second part is SIM card i.e.
Subscriber identity module.
 It is basically a chip which
consists all the details of the
subscriber’s contact like phone
number.
 Without SIM card, the mobile
equipment is useless.
 It consist authentication key
and algorithms for the
authentication check.
 Each SIM has a unique number
called IMSI (International
Mobile Subscriber Identity)

20. BASE TRANSRECEIVER STATION (BTS)
 Maintains air
interface and
minimize
transmission
problem.
 Time and frequency
synchronization.
 Radio level power
control.
 BTS identification.

21. BASE STATION CONTROLLER (BSC)
 It is connected to the
MSC.
 Controls one or more
BTS.
 Switches traffic and
signaling to/from BTSs
and MSC.
 Controls handover
performs by BTS.
 Frequency allocation
and power control.

22. MOBILE SWITCHING CENTER (MSC)
 The MSC basically performs the switching functions
of the system
 By controlling calls to and from other telephone and
data systems.
 It also had done functions such as network
interfacing and common channel signaling.
 Manages the interface between the GSM network
and the PSTN.
 The MSC controls the call set-up and routing
procedures in a manner similar to the functions of a
land network end office.

23. HOME LOCATION REGISTER (HLR)
 The HLR is database software that handles the
management of the mobile subscriber account.
 It stores the subscriber address, service type,
current location, forwarding addresses and billing
information.
 The SIM card of the mobile system is identified with
the International Mobile Subscriber Identity (IMSI)
number.

24. VISITOR LOCATION REGISTER (VLR)
 The VLR is temporary database software similar to
the HLR identifying the mobile subscriber visiting
inside the coverage area of an MSC.
 The VLR assigns a Temporary Mobile Subscriber
Identity (TMSI) that is used to avoid using IMSI on
the air.
 The Visitor Location Register maintains information
about mobile subscriber that is currently physically
in the region covered by the switching center.

25. AUTHENTICATION CENTER (AUC)
The AuC database holds different algorithms that are
used for ->
 authentication and encryptions of the mobile
subscribers.
 Verify the mobile users identity and ensure the
confidentially of each call. The AuC protects
network cellular operators from different type of
frauds. AuC holds the authentication and encryption
keys for all the subscribers in both the home and
visitor location registers.

26. EQUIPMENT IDENTITY REGISTER (EIR)
 The EIR is another database that keeps the information about the
identity of mobile equipment such as IMEI.
 Each mobile equipment is identified by IMEI which is memorized
by the manufacturer and cannot be removed. By the registration
mechanism, the MS always sends the IMEI to the network, so that
the EIR can memorize and assigns them to three different lists-
 WHITE LIST contains the IMEI of the phones who are
allowed to enter in the network.
 BLACK LIST contains the IMEI of the phones who are not
allowed to enter in the network, for example when mobile phone is
stolen then for not to use the mobile for illegal work by thief it's IMEI
number comes in black list.
 GREY LIST contains the IMEI of the phones momentarily not
allowed to enter in the network, for example because the software
version is too old or because they are in repair.

27. OPERATION AND MAINTENANCE SUBSYSTEM
 Dynamic monitoring and controlling of
Network.
 Operation and maintenance data function.
 Configuration Management.
 Fault report and alarm Handling.
 Performance supervision.
 Storage of Software and data.

28. THANK YOU