A standard form of communication on Integrated Services Digital Network (ISDN) communication systems. Basic Rate Interface ISDN (BRI-ISDN) connections consist of two B channels and one D channel. The B channels carry the voice or data between the customer premises and the telco’s central office (CO), while the D channel is used for establishing connections and signaling. BRI-ISDN is often referred to as 2B+D because of the channels that it uses.
The bandwidth of each B channel is 64 Kbps, so the total bandwidth of BRI-ISDN is twice that, 128 Kbps. This bandwidth can be used as two separate communication links of 64 Kbps each, or it can be combined using bonding into a single 128-Kbps communication link. The bandwidth of the D channel is 16 Kbps.
BRI-ISDN connections at customer premises can be connected directly to a switch at the telco’s central office, an ISDN call controller that is linked to the CO, an ISDN Private Branch Exchange (PBX), or some other signaling and communication equipment.