CHAPTER 10: Integrated Services Digital Network (ISDN)

In this chapter, the concept of the Integrated Services Digital Network (ISDN)  and the following topics shall be discussed:

• ·        Its original goals
• ·        how it can be used
• ·        some of the alternatives

ISDN (Integrated Services Digital Network) is a set of CCITT/ITU standards for digital transmission over ordinary telephone copper wire as well as over other media. Home and business users who install an ISDN adapter (in place of a telephone modem) receive Web pages at up to 128 Kbps compared with the maximum 56 Kbps rate of a modem connection. ISDN requires adapters at both ends of the transmission so your access provider also needs an ISDN adapter. ISDN is generally available from your phone company in most urban areas in the United States and Europe. In many areas where DSL and cable modem service are now offered, ISDN is no longer as popular an option as it was formerly.

There are two levels of service: the Basic Rate Interface (BRI), intended for the home and small enterprise, and the Primary Rate Interface (PRI), for larger users. Both rates include a number of B-channels and a D-channels. Each B-channel carries data, voice, and other services. Each D-channel carries control and signaling information.

The Basic Rate Interface consists of two 64 Kbps B-channels and one 16 Kbps D- channel. Thus, a Basic Rate user can have up to 128 Kbps service. The Primary Rate consists of 23 B-channels and one 64 Kpbs D-channel in the United States or 30 B-channels and 1 D-channel in Europe.

ISDN in concept is the integration of both analog or voice data together with digital data over the same network. Although the ISDN you can install is integrating these on a medium designed for analog transmission, broadband ISDN (BISDN) is intended to extend the integration of both services throughout the rest of the end-to-end path using fiber optic and radio media. Broadband ISDN encompasses frame relay service for high-speed data that can be sent in large bursts, the Fiber Distributed-Data Interface (FDDI), and the Synchronous Optical Network (SONET). BISDN is intended to support transmission from 2 Mbps up to much higher, but as yet unspecified, rates.

Source: http://searchenterprisewan.techtarget.com/definition/ISDN

ISDN is used heavily by the broadcast as a reliable way of switching low latency, high quality, long distance audio circuits. To reiterate, its concept is the integration of both analog or voice data together with digital data over the same network.

When compared to the old telephone dial-up service such as an Internet Service Provider (ISP), an ISDN for Internet Connection is a lot of greater. Using ISDN is just like using a broadband connection because it is as fast. And with such speed, there are innumerable things one can do. Aside from its faster connections which can’t be availed in normal modems, it is direct and with no dialing or engaged tone. It is suitable for gaming, video conferencing and streaming which can also comprise multiple recipients with no interference.

Thus, ISDN is a great technology−driven service that didn't really solve a business (or home) need. ISDN is not widely put into operation. But as we have noticed, there are some clear exceptions. The most notable is the aforementioned video conferencing. Internet access is also a possibility, but ISDN can't compete with xDSL technology in performance for the cost. The ISDN principal rate is used expansively in call centers, utilizing computer telephony integration to make the most of their efficiency.