In the Integrated Services Digital Network (ISDN), a high-speed communication channel comprising multiple aggregated low-speed channels to accommodate bandwidth-intensive applications such as file transfer, videoconferencing, and high-quality audio.
An H channel is formed of multiple bearer B channels bonded together in a primary rate access (PRA) or primary rate interface (PRI) frame in support of applications with bandwidth requirements that exceed the B channel rate of 64 kbit/s.
The channels, once bonded, remain so end-to-end, from transmitter to receiver, through the ISDN network.
The feature is known variously as multirate ISDN, Nx64, channel aggregation, and bonding.
H channels are implemented as: