A channel bank is a device used for multiplexing or demultiplexing a group of communication channels, including analog or digital telephone lines combined as a channel of higher bandwidth or digital bit rate. Channel banks are located in a telephone exchange or enterprise telephone closet, where individual telephone lines are separated from high-capacity telephone trunk lines originating from a central telephone office or enterprise private branch exchange (PBX).
Channel banks connect multiple voice channels through multiplexing and voice digitalization and are important digital communication transmission devices.
A channel bank is referred to as a bank because of its processing power that converts a bank of up to 24 or 32 individual channels to a digital and then analog format. These channels contain T1/E1 circuits. A channel bank may also multiplex channel groups into higher bandwidth analog channels.
There are different types of channel banks. Every channel bank contains formatting, which allows a user to achieve the desired results. Channel banks types include T1 circuits, each composed of 24 channels, and D4 channel banks containing digital signal level one (DS-1) signals. The DS-1 ensures that data is formatted with D4 format. Other types of channel banks are D2, D3, and digital carrier trunk. These channels are widely used by most telephone companies.