B channel

B channel (bearer) is a telecommunications term which refers to the ISDN channel in which the primary data or voice communication is carried. It has a bit rate of 64 kbit/s in full duplex. B channel (bearer) is a telecommunications term which refers to the ISDN channel in which the primary data or voice communication is carried. It has a bit rate of 64 kbit/s in full duplex. The term is applied primarily in relation to the ISDN access interfaces (PRA or PRI and BRA or BRI), since deeper in the PSTN network an ISDN bearer channel is essentially indistinguishable from any other bearer channel.