B channel

Definition of B channel in The Network Encyclopedia.

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What is B channel (in computer networking)?

Stands for bearer channel, a circuit-switched channel for carrying voice or data in Integrated Services Digital Network (ISDN) services. These channels are called bearer channels because they “bear,” or carry, the actual information being communicated between the customer premises and the telco’s central office (CO). B channels are standard, bidirectional, digital telephone channels that can carry digital information at a rate of 64 Kbps. Users with greater bandwidth needs can combine several B channels into larger data-carrying pipes. The two most common configurations are:

  • 2B+D:
    Combines two B channels to form a single data pipe with a total bandwidth of 128 Kbps


  • 23B+D:
    Combines 23 B channels to form a high-speed data pipe equivalent to a T1 line with a total bandwidth of 1.438 Mbps



B channels carry voice or data only, not signalling information. D channels carry information for establishment and control of ISDN connections.