Pass automatic telephone exchange

Automatic telephone exchange, automatic telephone exchange — the system of devices providing automatic (without participation of the operator or telephonists) connection and maintenance of telecommunication between the subscribers of this automatic telephone exchange using for this purpose special terminals – telephone sets, faxes, etc. (historically such station was called local automatic telephone exchange, that is local automatic telephone exchange where there is no exit to external telephone networks). If the automatic telephone exchange is one of elements of some telephone network – that this automatic telephone exchange has to provide connection and maintenance of communication with all subscribers of a network – as "", and connected to other automatic telephone exchanges of a network. The system of automatic telephone exchanges provides establishment, maintenance and a rupture of connections between devices, and also additional opportunities. It is provided with use of the telephone alarm system.