What is ISDN?
ISDN stands for Integrated Services Digital Network. It is a design for a completely digital telephone/telecommunications network. It is designed to carry voice, data, images, video, everything you could ever need. It is also designed to provide a single interface (in terms of both hardware and communication protocols) for hooking up your phone, your fax machine, your computer, your videophone, your video-on-demand system (someday), and your microwave. ISDN is about what the future phone network, and information superhighway, will look like (or would have looked like). ISDN was originally envisioned as a very fast service, but this was a long time ago when it was hoped to have fiber all the way to your house. It turned out that running all that fiber would be too expensive, so they designed ISDN to run on the copper wiring that you already have. Unfortunately, that slowed things down considerably – too slow for quality video, for instance. ISDN has been very slow in coming. The standar
ISDN [I*SD’N] n. 1. Integrated Services Digital Network. 2. A digital telephone service that provides fast, accurate data transmission over existing copper telephone wiring. 3. The way fast way to go online. • The Basics • What do I use it for? • Why should I use ISDN to access the Net? • More Details The Basics ISDN is based on a number of fundamental building blocks. First, there are two types of ISDN “channels” or communication paths: • B-channel The Bearer (“B”) channel is a 64 kbps channel which can be used for voice, video, data, or multimedia calls. B-channels can be aggregated together for even higher bandwidth applications. • D-channel The Delta (“D”) channel can be either a 16 kbps or 64 kbps channel used primarily for communications (or “signaling”) between switching equipment in the ISDN network and the ISDN equipment at your site. These ISDN channels are delivered to the user in one of two pre-defined configurations: • Basic Rate Interface (BRI) BRI is the ISDN service mos
ISDN stands for Integrated Services Digital Network and is, put simply, is a digital equivalent to a telephone line. ISDN services are available from most telecomms operators in most parts of the world. What is descibed as ‘an ISDN line’ is actually made up of two different types of channels. D-channels are used for signalling and call setup. B-channels are the data channels and are used for the transfer of your data (and voice calls – ISDN lines can still carry those too!) Each B-channel can be used independently as a separate data channel (or telephone line), so you can have two separate connections (or calls) in progress at the same time. Typically ISDN is available in two seperate forms. Basic rate ISDN (also called BRI or Basic Rate Interface or ISDN-2 in Europe) consists of two B-channels and one D-channels. ISDN audio codecs are generally connected to BRIs. The second type of ISDN service is called Primary Rate Interface (PRI or ISDN-30 in Europe). This is used by bigger install
ISDN is an all digital switched telephone network provided by the telephone company. Each ISDN line has three channels: two 64 kb/s ‘B’, or bearer, channels, and one 16 kb/s ‘D’, or delta channel. The two ‘B’ channels are for user data, and can be used independently from each other as two separate data channels. The phone company uses the ‘D’ channel for signaling, such as call setup and termination, billing and configuration. Unlike regular telephone service where the customer equipment and line is analog, ISDN is truly end-to-end digital service. What are terminal adapters and what is an NT1? An ISDN terminal adapter is similar in function to a telephone modem. Call setup (dialing), rate negotiation, and call termination functions are all performed by the terminal adapter. In addition, the terminal adapter converts the user data into a format required by the network for transmission. The NT1 is an interface converter. The three channels of ISDN are all combined onto a single twisted
