Explain the numbering plan for ISDN address structure.
The numbering plan for ISDN is evolved with using the following guidelines:
1. This is based on, and is an improvement of, the telephone numbering plan. This is independent of the nature of the services (for example voice, data or facsimile) or the performance characteristics of the connection (for example:. 32 kbps voice or 64 kbps voice).
2. This is independent of routing, that is the numbering or addressing does not identify the intermediate exchanges by that the services are to be put through.
3. This is a sequence of decimal digits. No other characters or alphabet are permitted as part of the address.
4. Its design is interworking in between ISDNs needs only the use of ISDN number and no addressing signals or other additional digits.