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Telecommunication

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Gaurav Sharma

This document summarizes how a fixed landline call is setup and routed through the telecommunications network. It first goes to the nearest switching center (PSTN). If the caller and receiver are in the same base switching center (BSC), the call is completed. Otherwise, it is transferred to the main switching center (MSC) and then to the receiver's prior BSC. For mobile calls, the call transfer is handled by the mobile telephone switching office (MTSO) and base transceiver stations (BTSs). The telephone exchange checks if numbers are valid and sends busy tones if lines are engaged. Calls are connected between telephones via remote exchanges.

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FIXED LANDLINE NETWORK
CALL SETUP When a subscriber calls to another subscriber first its request goes to the nearest switching centre that is PSTN (Public Switching Telecommunication Network). Then it processes the caller and subscribers number if it exists in the same BSC then call setup is completed. If subscriber is not in the same BSC (Base Switching Centre) then call transfer to MSC (Main Switching Centre) then it transfers the call to prior BSC then call setup is completed. If Caller calls to a mobile subscriber then call transfer is done by MTSO now call transfer is done on BTSs (Base Transceiver Station) and call setup is completed.
Fig:- HOW LINE REACHES FROM SUBSCRIBER TO EXCHANGE
TELEPHONE EXCHANGE Whenever the user dials a no it checks whether it is valid user or not If receiver is busy then it sends a busy tone Whenever telephone dials a number then it is received by the telephone & it connect to the relevant telephone via remote exchange
MDF(MAIN DISTRIBUTION FRAME) All the telephone channel are terminated at the MDF It is a cable rack where all the telephone channels are terminated If a new connection is given at the exchange side &cable side relevant point are connected by using another small cable these cables are called Jumper MDF is a passive device (no need of electrical power)
CABINET 50 pair 100 pair 200 pair etc. multipair cables are drawn from MDF to cabinet From cabinet 10 pair 5 pair cables are drawn up to distribution Primary Cable:- MDF to Cabinet secondary cable:- Cabinet to DP
DP(Distribution point) 5 pair or 10 pair cable is laid from cabinet to DP that means there are 10 loops , 5 loops in a dp When a new connection is provided a pair of cable is drawn from DP to home this means that 10 to 5 telephone new connection can be provided from a dp
HOW A TELECOM EXCHANGE WORKS:- It require -48 Vdc. A telephone exchange or telephone switch is a system of electronic componen ts that connects telephone calls. A central office is the physical building used to house inside plant equipment including telephone switches, which make telephone calls work in the sense of making connections and relaying the speech information. The basic block diagram for a telecom exchange is as follows-
POWER PLANT:- It provides -48V to the switch rooms and 48V to the connections. Batteries are artificially discharged once in a year for their maintenance. Cooling is provided through fans & AC. There is earth region too for protection. OMC (Operation and Maintenance Control) It contains input-output processor terminals, visual display units, printers, cartridges, etc. It controls the entire operation of exchange data and billing data. The new connections, adding and removing of facilities to the subscriber is done in the OMC room.
Switch It provides the switching facility and connection to the outside of the exchange. The switch room contains actual telephone switching hardware such as cabinets, racks, slots and cards. Switching is the most important part of the exchange process.

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Telecommunication

  • 2. CALL SETUP When a subscriber calls to another subscriber first its request goes to the nearest switching centre that is PSTN (Public Switching Telecommunication Network). Then it processes the caller and subscribers number if it exists in the same BSC then call setup is completed. If subscriber is not in the same BSC (Base Switching Centre) then call transfer to MSC (Main Switching Centre) then it transfers the call to prior BSC then call setup is completed. If Caller calls to a mobile subscriber then call transfer is done by MTSO now call transfer is done on BTSs (Base Transceiver Station) and call setup is completed.
  • 3. Fig:- HOW LINE REACHES FROM SUBSCRIBER TO EXCHANGE
  • 4. TELEPHONE EXCHANGE Whenever the user dials a no it checks whether it is valid user or not If receiver is busy then it sends a busy tone Whenever telephone dials a number then it is received by the telephone & it connect to the relevant telephone via remote exchange
  • 5. MDF(MAIN DISTRIBUTION FRAME) All the telephone channel are terminated at the MDF It is a cable rack where all the telephone channels are terminated If a new connection is given at the exchange side &cable side relevant point are connected by using another small cable these cables are called Jumper MDF is a passive device (no need of electrical power)
  • 6. CABINET 50 pair 100 pair 200 pair etc. multipair cables are drawn from MDF to cabinet From cabinet 10 pair 5 pair cables are drawn up to distribution Primary Cable:- MDF to Cabinet secondary cable:- Cabinet to DP
  • 7. DP(Distribution point) 5 pair or 10 pair cable is laid from cabinet to DP that means there are 10 loops , 5 loops in a dp When a new connection is provided a pair of cable is drawn from DP to home this means that 10 to 5 telephone new connection can be provided from a dp
  • 8. HOW A TELECOM EXCHANGE WORKS:- It require -48 Vdc. A telephone exchange or telephone switch is a system of electronic componen ts that connects telephone calls. A central office is the physical building used to house inside plant equipment including telephone switches, which make telephone calls work in the sense of making connections and relaying the speech information. The basic block diagram for a telecom exchange is as follows-
  • 9. POWER PLANT:- It provides -48V to the switch rooms and 48V to the connections. Batteries are artificially discharged once in a year for their maintenance. Cooling is provided through fans & AC. There is earth region too for protection. OMC (Operation and Maintenance Control) It contains input-output processor terminals, visual display units, printers, cartridges, etc. It controls the entire operation of exchange data and billing data. The new connections, adding and removing of facilities to the subscriber is done in the OMC room.
  • 10. Switch It provides the switching facility and connection to the outside of the exchange. The switch room contains actual telephone switching hardware such as cabinets, racks, slots and cards. Switching is the most important part of the exchange process.