Customer premises equipment (CPE) used to route calls both within an organization and to and from the outside telephone network. A key system is a scaled-down version of a PBX, usually with less functionality, which is geared toward smaller organizations. A key system can be either analog or digital. Some digital key systems can terminate digital as well as analog connections. Moreover, key systems work in conjunction with channel banks to distribute channels from the T1/E1 circuit for voice, video, fax, and data.