Integrated Services Digital Network (ISDN)

The ISDN network is a fully digital communications link standard for interconnection between the local exchange and the home or office. It provides a guaranteed data rate of a minimum of 64 kbps and does away with the need for separate modem cards within computers or fax machines. Voice is digitized at the source (that is, within the telephone) and so there is perfect reception quality under all conditions. It is likely that ISDN will replace many of the existing analogue connections to the user over the next few years. The ISDN system also has a separate set of service standards with the 2B+D service intended for small office and home use, and the primary rate services intended for major business use.