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•On October 1, 2000 the Department of Telecom Operations,Government of India became a corporation and waschristened Bharat Sanchar Nigam Limited (BSNL).

•

 At present the BSNL is the World's Largest Seventh and India's FirstTelecommunication Company.

•Presently the plain old, countrywide telephone service is beingprovided through 32,000 electronic exchanges, 326 Digital Trunk

 Automatic Exchanges(TAX), Digitalized Public Switched TelephoneNetwork (PSTN) all interlinked by over 2.4 lakhs km of Optical FiberCable, with a host of Phone Plus value additions to our valuedCustomers.

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SECTIONS VISITED :

E-10B SWITCHING

OCB SWITCHING

MAIN DISTRIBUTION FRAME

TRANSMISSION SECTIONMOBILE SECTION

POWER STATION

BROAD BAND

COSTUMER CARE

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 Caller

/

D.P/

Pillar

/

MDF

/

Exchange/

Tax

/

Exchange

/

MDF\

Pillar

\

D.P

\

Receiver

:

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  DESCRIPTION OF VARIOUS BLOCKS

•

DP (Distribution Panel)Distribution point box commonly know as D.P. box is aterminal arrangement where under ground cable pairs areconnected to overhead wires or drop wires for providing

connections at subscribers premises.

TAX (Trunk auto exchange)

This section deals when a caller picks up the receiver, gets the

dial tone and how the call is made and processed.

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• Pillar

Pillar is fabricated from steel or cast from casings enclosing aframe-work on which cable terminal boxes are mounted. Theterm "pillar" is used with reference to a flexibility point whereMDF's cables and DP's cables are interconnected.

• Exchange

Card is a basic functional unit of the exchange. Various

cards are utilized for various purposes e.g. Subscribercards are utilized for termination of subscriber's cablescoming from MDF

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To obtain flexibility in interconnecting, external line plants and theexchange equipment and between different circuits in the exchange itself,certain arrangements is made by the use of iron frames. These iron framesare called main distribution frames,

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MAIN DISTRIBUTION FRAME 

The primary function of MDF is:

The fault of telephone number is removed in the MDF

it is called as Fault Remove For removing the fault of

telephone number, we use the testing These testing are

T.T.Y. testing, Group testing, etc.

For any type of testing firstly we need the vertical no. or

the live tester, printer and computer test N.E. number of

that particular telephone number.

The telephone numbers are also disconnected in the MDF

 because of some specific reason. 

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  PARTS OF THE MDF 

 VERTICAL SIDE: 

The vertical side connected to the underground cable. This cable ishaving 100 pairs . These pair is distributed when we allot the telephonenumber to the subscriber.

•  All the part from vertical side to the subscriber are generally called outdoor

section.

• 1 vertical has 10 tag block Each tag block has 10 rows and each row has 10tags. So each tag block has 100 tags.

•

  Connection between vertical side & subscribers are provided by jelly filledcables.

• This wires are first terminated in cabinet box, then according torequirements the group of the wires are terminated in pillar box & from here

connections are given to the subscribers via DP box.

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VERTICAL SIDE

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• All the parts from LEN to the exchange is called indoor section.

• The connection of subscriber from exchange is terminated on this

side of MDF.

• In 1 tag block there are 128 tags. Each tag block is divided in 4segments. That is 0, 1,2 & 3 and in each segments. There are sixteen

tags.

• On the vertical side there is 100 tag in one vertical tag block where

as on the LEN side there is 128 tags on each LEN block. The reasonfor this difference is that there is always a reserve of spare capacity in

the external cables to cover fluctuations in the distribution of the

subscribers lines as between the different localities served by the

cables.

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HORIZONTAL SIDE

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PROTECTIVE DEVICE USED ON M.D.F.

• FUSES :-

A fuse is a small length of thin wire which melts if there is an excess of

current and disconnect the equipment before possible damage.

The rated current of fuse is the maximum current which it can carry

without melting or fusing.

• GAS DISCHARGE TUBE :- 

Gas discharge protectors are used as protective device to protect the

communication lines and equipments from damages due to high

voltages. The gas discharge protector essentially consists of two of

three tungsten electrodes sealed in a special glass envelope or ceramic

envelop[e containing a mixture of inert gases , mainly neon.

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POWERPLANT

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 ANY QUERIES !