History of ISDN:
1.The first service was introduced by British Telecom in June 1985.
2.Another early pre-standard ISDN service was project Victoria, offered by Pacific Bell in 1986 in Danvilll, California.
3.ISDN availability is just over 70% in North American.
What is ISDN?
Defination:
Integrated Services Digital Network (ISDN) is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network.
OR
A network, in general evolving from a telephony Integrated Digital Network (IDN), that provides end to end digital connectivity to support a wide range of services, including voice and non voice services, to which users have access by a limited set of standard multi purpose user net work interfaces by CCITT.
1) ISDN stands for Integrated Services Digital Network. It is a design for completely digital telephone/telecommunications network.
2) It is designed to carry voice, data, images, video, everything you could ever need.
3) It is also designed to provide a single interface for hooking up your phone, your fax machine, your computer, your videophone, your video-on-demand system and your microwave.
4) ISDN is about what the future phone
network, and information superhighway, will look like (or would have looked like).
5) 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.
6) 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.
7) Unfortunately, that slowed things down considerably - too slow for quality video, for instance.
8) ISDN has been very slow in coming.
9) The standards organizations have
taken their time in coming up with the standards.
10) In fact, many people consider them to be out of date already. But on the other side of the coin, the phone companies (especially in the U.S.) have been very slow at designing products and services, or marketing them with ISDN in mind.
Two kinds of ISDN
N-ISDN provides lower speed services (56Kbps - 2.0Mbps)
Narrowband ISDN as a means of switched WAN access in data networks, it has fast call setup, flexibility in support different services and ability to support existing WAN protocols. Frame Relay &X.25.
B-ISDN provides high speed services(2 – 600 Mbps)
B-ISDN is Broadband ISDN. (The older ISDN is often called Narrowband ISDN), This is not simply faster ISDN, or ISDN with the
copper to your home finally upgraded to fiber.
B-ISDN is a complete redesign. It is still capable of providing all the integrated
services (voice, data, video, etc.) through a single interface just like ISDN was supposed to. But it will do it a lot faster than ISDN could. Of course, that copper to your house will still have to be replaced with fiber. But B-ISDN is still in development - it seems to be moving faster than ISDN, but it is still quite a ways off.
