A Multiplexer. A device which puts many slow-speed voice or data conversations onto one high-speed link and controls the flow of those "conversations." Typically the device that sits between a digital circuit - say a T1 - and a couple of dozen voice grade lines coming out of a PBX. One side of the channel bank will be connections for terminating two pairs of wires or a coaxial cable - those bringing the T-1 carrier in. On the other side are connections for terminating multiple tip and ring single line analog phone lines or several digital data streams. Sometimes you need channel banks. Sometimes, you don't. For example, if you are shipping a bundle of voice conversations from one digital PBX to another across town in a T-1 format - and both PBXs recognize the signal - then you will probably not need a channel bank. You'll need a Channel Service Unit (CSU), If one, or both, of the PBXs is analog, then you will need a channel bank at the end of the ******
name of a magazine published by Telecom library Inc. Source for majority of these definitions. See also Central Office or Public Exchange.