intercommunicating system[¦in·tər·kə′myü·nə‚kād·iŋ ‚sis·təm]
A privately owned system that allows voice communication between a limited number of locations, usually within a relatively small area, such as a building, office, or residence. Intercommunicating systems are generally known as intercoms. Intercom systems can vary widely in complexity, features, and technology. Though limited in size and scope, intercom systems can provide easy and reliable communication for their users.
An extremely simple intercom is a two-station arrangement in which one station is connected to the other via a dedicated wire. Other systems have multiple stations, as many as 10 to 20, any of which can connect with any other station. The user must dial a one- or two-digit code to signal the intended destination.
Still other intercom systems work in conjunction with key and hybrid key telephone/private branch exchange telephone systems. They support internal station-to-station calling rather than access to outside lines. Normally the telephone intercom is incorporated in the same telephone instrument that is used to access the public switched network.
A third type of intercom is the wireless intercom system for intrabuilding communications, which consists of a base unit radio transmitter, equipped with an antenna, and a number of roving units tuned to different frequencies. The base can selectively communicate with individual roving units by dialing the code corresponding to each roving unit's specific frequency. See Mobile radio