BRI (Basic Rate Interface)

Integrated Service

Basic Rate Interface (BRI, 2B+D, 2B1D) or Basic RateAccess is an Integrated Services Digital Network (ISDN) configuration intended primarily for use in subscriber lines similar to those that have long been used for voice-grade telephone service.

Short for Basic Rate Interface, BRI  is one of the two levels of services provided by Integrated Services Digital Network (ISDN). BRI is made for home and small-scale enterprise use. It consists of two bearer channels (B channels) and one data channel (D channel) for transmission of data. The B channel carries data, voice, and other services, while the D channel carries controlling and signaling data. It  provides up to two 64 KBPS B-channels and one 16-KBPS D channel over an ordinary two-wire telephone line. B-channels carry circuit-oriented data or voice traffic while D-channels carry call control signals.

Basic Rate Interface (BRI): Single Line Service uses an ISDN digital network architecture to enable reliable data communications without the expense of dedicated lines, modems and cabling, while accelerating both voice and data far beyond the speed of standard telephone lines. Multiple communications can share a single line simultaneously, including voice, video, and data, with digital clarity. Multiple B channels for high-speed circuit-switched data, complemented with a separate D channel for low-speed packet-switched data, let you support a broad range of applications with optimal efficiency. 

ISDN has enabled the reliable transmission of data where multiple users can make use of the service lines at the same time. This network architecture is economical for small industries and homes where dedicated lines, modems and cabling expenses must be kept low. A bearer channel has a bit rate of 64 Kbps, whereas a data channel is 16 Kbps. Two bearer channels can be combined by channel bonding to give an aggregated data rate of 128 Kbps. B channels have dedicated bandwidth and transmit data via a formatted and circuit-switched channel, whereas D channels transmit data in the form of packets. The format of data communication in the D channel has become the basic type of frame relay.