Q 5 (a). Describe the ISDN ?
Integrated Services Digital Network (ISDN)
Integrated Services Digital Network (ISDN) is a telephone system network. It is a wide area network which is widely available. Before to the ISDN, the telephone system was viewed as a way to transport only voice, with some special services available for data. The key feature of the ISDN is that it integrates speech and data on the same lines, adding features that were not available in the classic telephone system.