ISDN is the abbreviation of Integrated Services Digital Network which is a set of communications standard for instantaneous digital transmission of data, audio, video, and other services related to network, in excess of the conventional circuits of the community switched telephone network. ISDN (Integrated Services Digital Network) was introduced by CCITT in 1988. ISDN (Integrated Services Digital Network) is a method to transfer voice data with some particular services accessible for data. The major feature of ISDN (Integrated Services Digital Network) is that it put together speech and information on the same line which were not presented in classic telephone system.
The main element of ISDN (Integrated Services Digital Network) services are ability to deliver maximum data within the combination of voice, data, video, fax, over a single line while it provides at least two instantaneous connections. User can attach several devices to the line according to their need instead of purchasing many analog phone lines.
ISDN (Integrated Services Digital Network) make available access to packet switched networks because it is a circuit switched telephone network system. Therefore it provides better quality of voice data than an analog phone. ISDN (Integrated Services Digital Network) also offer 64 kbits/s and in some countries it provides 128 kbites/s in both uploading and downloading. The ISDN-B channel is responsible to provide greater data rate. ISDN (Integrated Services Digital Network) is a best suit of digital services existing on layer 1, layer2, and layer3 of OSI reference model.
- The basic advantage of ISDN is to facilitate the user with multiple digital channels. These channels can operate concurrently through the same one copper wire pair.
- The digital signals broadcasting transversely the telephone lines.
- ISDN provides high data rate because of digital scheme which is 56kbps.
- ISDN network lines are able to switch manifold devices on the single line such as faxes, computers, cash registers credit cards readers, and many other devices. These all devices can work together and directly be connected to a single line.
- ISDN takes only 2 seconds to launch a connection while other modems take 30 to 60 second for establishment.
- The disadvantage of ISDN lines is that it is very costly than the other typical telephone system.
- ISDN requires specialized digital devices just like Telephone Company.