The trunk code is 2 to 4 digits. The telephone exchange code and last n digits of subscriber number together called subscriber number and is from 6 t0 8 digits. Hence national number to call a subscriber is 8 to 12 digits. To call a subscriber in another SDCA, prefix '0' must be dialled first.
SDCA code. Digit A can have any value from 1 to 8. Digit B, C and D can have any value between 0 to 9. AB codes can have any value between 11 to 89 (79 trunk codes). The code 10 is earmarked for carrier access code for NLD service and ILD service. Code 11, 20, 22, 33, 40, 44, 79 and 80 (8 codes) are used presently. 39, 50, 60, 69 and 70 (5 codes) are available for allotment to SDCA's with 3-digit code depending on the requirement. Certain three digit spare codes like 555, 666 and 888 are not to be used as SDCA codes. These are reserved for future services.
Telephone exchange code. Digit E can have any value between 2 to 6. The 0, 1, 7, 8, 9 are not allowed as '0' is used as trunk prefix, level '1' is used for special services, 7 and 8 are kept spare for future services and level '9' is used for cellular mobile services, paging services and access to adjacent areas. Digit F, G and H can have any value from 0 to 9. EFG can take value between 200 and 699 (500 exchange codes).
Last n digits of subscriber number. Digit P, Q, R, S and T can have any value from
Dialling. For a call within a local area i.e. SDCA, subscriber number (Telephone exchange code + last n digits of subscriber code) only need to be dialled. Thus the number of digits needed to be dial is 6 to 8.
For calls outside the SDCA, 0 + NSN is need to be dialled (NSN = SDCA code + Telephone exchange code + last n digit of subscriber number). However, access to adjacent areas can also be possible by dialling '95' followed by NSN.
Note. It should be noted that the information given above are according to the matrials from the websites, magazines and reference books only. These informations are subject to change according to the change in Government policies and the change in ITU recommendations. The readers of this book are suggested to refer the related websites for updated changes in numbering plans.
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