key telephone system (KTS)

Definition

Smaller, cheaper, but less flexible alternative to a private branch exchange (PBX) phone system. A KTS is equipped with several buttons that allow a caller to directly select outgoing lines or incoming calls, and use intercom and conference facilities. Unlike in a PBX, a user does not have to dial '9' to access an outgoing line, but the incoming calls are not automatically routed to the called party. KTS are user-installable and allow handling of multiple lines without paying a surcharge to the telephone company. However, the hunt-group service cannot be provided on them.