Channel Banks

The transmission terminal equipment, typically in a telephone central office, which accepts 12 or 24 voice inputs and combines them into a single higher-bandwidth facility (usually a T1).   

Older analog transmission systems, N2 and N3 channel banks used frequency division multiplexing to combine 12 and 24 voice-grade inputs, respectively, into a single facility. But today, all channel banks use TDM.

Modern channel banks can mix and match groups of DS0's, so that the T1 access circuits can be segmented into several sub-rate data streams.

A digital channel bank such as the D4 Channel Bank supports 24 individual channel inputs.