ISDN-technology, networking concepts and applications

Abstract

ISDN — the Integrated Services Digital Network — evolves from the all-digital Telephone Network. Its advantages are the integration of voice, text, facsimile and data services within one network, the so-called narrow-band ISDN based on 64 kbps circuit switched channels. The usage of the existing subscriber lines which will be operated at 192 kbps, allows for 2 B (64 kbps) and 1 D (16 kbps) channels for each subscriber (Basic access). The B-channels can be used for any voice, data, text or facsimile connections simultaneously, whereas the D-channel allows for signalling at any time. Within the ISDN, interoffice signalling is also separated from the user information paths; thus, an end-to-end packet switched signalling network controls all connection management. Therefore, the narrow-band ISDN can easily be extended to a broad-band ISDN by extending the switched network by broadband switching and transmission facilities.

Most countries start their ISDN pilot and regular services during the next years. It is anticipated that ISDN will quickly grow and take over a number of non-voice services which are today operated on different networks. Particularly, it will be of highest interest, how packet switched services can be integrated into the ISDN. There are several options in the subscriber access area (D-channel, B-channels) and within the network itself (packet switched subnetwork, signalling network or switched B-channels).

This paper addresses the following aspects: Transition from analog to digital, service concepts, network concepts, technology, interworking and research.