There are various kinds of interfaces defined by ISDN such as Basic Rate Interface (BRI), Primary Rate Interface (PRI), and Broadband (B-ISDN).
Basic Rate Interface (BRI)
Basic Rate Interface of ISDN contains two 64-B channel and one D- channel for broadcasting control information. In some circumstances it refers to as 2B+D. ISDN BRI (Basic Rate Interface) identifies the following network interface. Basic Rate Interface (BRI) is very popular in Europe but much les common in North America. In Japan it is known as INS64.
ISDN-U Interface consists of two wires among the exchange and network terminating unit. ISDN-U interfaces generally the discrimination point in non North American networks.
ISDN-T interface is a digital correspondent of a modem. Among terminal adapter and computing devices ISDN-T interface is a serial device
It consists of four wire bus that ISDN customer devices plug into. The ISDN-T and ISDN-S interfaces indication points are usually put into practices as a single interface on NTI.
ISDN-R interface is appointed among a terminal adapter and non ISDN devices which offers transformation to and from such a device.
Primary Rate Interface (PRI) of ISDN
ISDN Primary Rate Interface (PRI) contains 23 B-channel and one D-channel in US and in Europe it contains 30 B-channel and one D-channel. Primary Rate Interface is very well-liked all over the world particularly for PSTN circuits to PBXs. Many networks all through the world use the term ISDN to refer low bandwidth circuits.
An additional version of ISDN is called B-ISDN (Broadband ISDN) make use of broadband communications. Broadband is capable to carry broadcasting rate of 1.5 Mbps. B-ISDN (Broadband ISDN) mainly have need of fiber optic cables. To get access it is compulsory to subscribe the ISDN phone line and consumer should required special devices for it such as terminal adapter which is used for communication with the telephone company switch or other ISDN devices. Most broadband channel carries 64 kbit/s signals.