The B channel, also called bearer channel or basic channel, is a user channel of the ISDN basic access or primary multiplex access.
In the basic access, two B-channels with a transmission speed of 64 kbit/s each are provided for the transparent transmission of all types of information such as voice, data, texts, graphics, etc.. Both B channels can be used simultaneously or each separately. It is also possible to bundle both B channels to increase the data rate.
In contrast to the basic connection, the primary multiplex connection offers 30 B-channels, which corresponds to a cumulative data rate of 2.048 Mbps.