2 Network Plans I

Concept of SDCA and LDCA „

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Indian Telecom Network is divided into number of LDCAs. Each LDCA consists of one or more SDCAs, which are also known as local areas. Each SDCA has one or more number of exchanges. Each LDCA has a Long Distance Charging Centre (LDCC), which is a Trunk Automatic Exchange (TAX).

Concept of SDCA and LDCA „

ITU Recommendation E.164 provides four options for National Destination Code (NDC) structure. India has adopted type-2 structure for PSTN where NDC is the trunk (Area) code assigned to each SDCA. Each SDCA is allotted a unique trunk code. There are at present 2642 SDCAs distributed in 322 LDCAs.

Concept of SDCA and LDCA „

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Each SDCA has a Short Distance Charging Centre (SDCC). Normally each SDCC is an integrated localcum-tandem or a transit switch. In certain cases SDCC itself may also be LDCC. Each SDCA normally covers one or more taluka or other administrative areas. The size of SDCA generally varies between 800 sq. kms to 2000 sq.

LINKED NUMBERING SCHEME FOR PSTN „

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Normally the N(S)N is of 10 digits including 2 to 4-digit National Destination Code (SDCA Code) and 8 to 6-digit subscriber number. This excludes the access code ‘0’. Most of the SDCA’s have 4-digit trunk code, leaving 6 digits for subscriber number.

Numbering Plan Area (NPA) „

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Numbers in an NPA are not duplicated and are called ‘subscriber numbers’. To make a call from one subscriber to another subscriber in the same NPA, only the subscriber number needs to be dialed. NPA relates to specific geographic or administrative area as far as possible. At present the NPA is same as SDCA.

DIALLING „ „

Dialling within SDCA For a call within a local area i.e. SDCA, subscriber number only will need to be dialled. The number of dialled digits will thus be 6, 7 or 8.

CALL ROUTING WITHIN EXCHANGE

LE / TANDOM

LOCAL EXCHANGE LE SDCA

LE

CALL ROUTING OUTSIDE EXCHANGE WITHIN SDCA

LE / TANDOM

LOCAL EXCHANGE LE SDCA

LE

DIALLING „ „

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Dialling outside SDCA For calls outside the SDCA, ‘0+N(S)N’ as per ITU E.164 or ‘0+10+CIC+N(S)N’ need to be dialled. However, access to adjacent areas are also be on level ‘95’ followed by N(S)N. All such adjacent areas shall have to be accessible by dialling N(S)N with ‘0’ prefix or through carrier selection

CALL ROUTING OUTSIDE SDCA WITHIN LDCA SDCA

SDCA

SDCA LDCC SDCA

SDCA SDCA SDCA SDCA

CALL ROUTING OUTSIDE LDCA LDCC

SDCC

LE

LDCC

SDCC

LE

NUMBERING „

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Certain three digit spare codes like 555, 666 and 888 are not to be used as SDCA codes. These are reserved for future services First digit of the telephone exchange codes can have any value between ‘2’ to ‘6’. Digit ‘2’ has been allocated as the first digit for BSNL/ MTNL numbers. For the private BSOs, digit ‘3’ or ‘5’ are allotted First digit in subscriber number should not be ‘0’, ‘1’, ‘7’, ‘8’ and ‘9’.

Objective of Numbering Plan „

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The new National Numbering Plan will be able to meet the challenges of multioperator, multi-service environment and will be flexible enough to allow for scalability for next 30 years without any change in its basic structure. The other main objectives of the plan are – i) To plan in conformity with relevant and applicable ITU standards to the extent possible. ii) To meet the challenges of the changing telecom environment. iii) To reserve numbering capacity to meet the undefined future needs. iv) To support effective competition by fair access to numbering resources. v) To meet subscriber needs for a meaningful and user-friendly

Salient features of the National Numbering Plan „

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It is a SDCA based linked numbering scheme. N(S)N is 10-digit for both the basic as well as cellular mobile services. · The Subscriber Number (SN) for basic services will be of 6, 7 or 8 digits depending upon the length of SDCA code. ·Basic to cellular mobile service calls shall use prefix ‘0’ only if Point of Interconnect (POI) is not available in the same Long Distance Charging Area (LDCA) from where the call is originated.

Salient features of the National Numbering Plan „

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Basic services shall be accessed by cellular mobile using ‘0’. Carrier Access Code (CAC) for NLD and ILD has been defined as ‘10’. All the service providers shall use ‘100’, ‘101’ and ‘102’ for Police, Fire and Ambulance services respectively.

Salient features of the National Numbering Plan „

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‘107X’ has been defined for emergency information services like earthquake, floods, air and train accident etc. Certain level ‘1’ codes are earmarked for all service providers to offer various subscriber related services, as per their choice, within their network.

NATIONAL NUMBERING SCHEME „ „ „

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Level ‘0’: Sub level ‘000’: The prefix ‘000’ shall be used for home country direct service (Bilateral) and international toll free service (Bilateral). The format used is: ‘000 + Country Code + Operator Code’

NATIONAL NUMBERING SCHEME „

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Sub level ‘0010’ - INTERNATIONAL CARRIER ACCESS (Prefix) CODE: The prefix ‘0010’ shall be used for selection of international carrier. It will be followed by International Carrier Identification Code (ICIC), Country Code (CC) and N(S)N. The format shall be as under: Prefix International Carrier Identification Code + Country Code + National(Significant)Number 0010 ICIC CC N(S)N

NATIONAL NUMBERING SCHEME „ „

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Sub level ‘00’ - INTERNATIONAL PREFIX: The prefix ‘00’ shall be used for International dialling. It will be followed by country code and the N(S)N of the country to which that call is attempted. The format is as per ITU Recommendation E.164: Prefix Country Code + National(Significant)Number 00 CC N(S)N

NATIONAL NUMBERING SCHEME „

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Sub level ‘010’ - NATIONAL CARRIER ACCESS (Prefix) CODE: The prefix ‘010’ shall be used for selection of national long distance carrier. It will be followed by (National) Carrier Identification Code (CIC) and N(S) N. The format shall be as under: Prefix Carrier Identification Code + National(Significant)Number 010 CIC N(S)N

NATIONAL NUMBERING SCHEME „ „

Sub level ‘0’ - NATIONAL PREFIX: The prefix ‘0’ shall be used for national long distance calls (cellular mobile as well as basic services), intra service area (Circle) long distance calls of basic services, cellular mobile to basic services calls and calls from basic services to cellular mobile (depending upon point of interconnect).

NATIONAL NUMBERING SCHEME „ „ „

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The format shall be as under: For basic services (PSTN) long distance calls: Prefix National Destination Code Subscriber Number 0 + 2/ 3/ 4-digit trunk (SDCA) code + 8/ 7/ 6-digit subscriber number For basic services to cellular mobile calls if Point of Interconnect is not available in the same LDCA from where the call is originated: Prefix PLMN Access Code + MSC Code + Subscriber Number 0 + 2-digit ( e.g. 98, 94 etc. ) + 3-digit + 5-digit For cellular mobile to cellular mobile calls outside the service area from where the call is originated: Prefix PLMN Access Code + MSC Code + Subscriber Number 0 2-digit ( e.g. 98, 94 etc ) + 3-digit + 5-digit

NATIONAL NUMBERING SCHEME „

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For cellular mobile to basic services calls: Prefix National Destination Code + Subscriber Number 0 2/ 3/ 4-digit trunk (SDCA) + code 8/ 7/ 6-digit

NATIONAL NUMBERING SCHEME „

Sub level ‘011’ to ‘089’ - GEOGRAPHICAL NUMBER RANGE:

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These codes are also called trunk codes and identify a specified geographical area where a call is to be terminated. The national telecom network in India has been divided as under: SDCA: Short Distance Charging Area also called local area LDCA: Long Distance Charging Area comprising of one or several SDCAs

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NATIONAL NUMBERING SCHEME „

Sub level ‘09’ - SERVICE (PREFIX) CODES:

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The level range ‘09’ is to be used for cellular mobile services, satellite based services and Intelligent Network (IN) services like premium rate & universal number (long distance).

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Level ‘1’ SPECIAL SERVICES:

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Level ‘1’ is used for accessing special services like emergency services, supplementary services, inquiry and operator-assisted services. Some sub levels have been allocated for use by access providers (operators). These levels can be used for providing the services within their network.

NATIONAL NUMBERING SCHEME „

Level ‘2’ to ‘6’ - PSTN NUMBER:

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The numbers starting from ‘2’ to ‘6’ are reserved for PSTN within SDCA. At present the PSTN numbers in SDCAs vary between 6 to 8 digits so that the total N(S)N is 10-digit

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Level ‘7’ & ‘8’:

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At present, level ‘7’ & ‘8’ are not being allocated and the same are reserved for new services.

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Level ‘9’ SERVICES:

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The range of numbers in level ‘9’ except ‘90’, ‘95’ and ‘96’ are reserved for cellular mobile services.