Telephone line interconnection system - embraces centralised and non-centralised connections using coupling unit, internal signal switching control and memories in central control

摘要

The circuit arrangement is for telephone installations with centralised and decentralized control units and connections between similar and different units for both outgoing and incoming traffic. The central control unit (ZS) includes an instrument memory (GSp), a terminal instrument memory (EGSp), and a control stage (EW) connected through an exchange line (An1) to the common data line TSt, D1) for a number of subscriber lines (TA, TB, TC, TD). The individual subscriber lines are connected to a coupling unit (NA) which enables each subscriber line to be connected to one of the others or to the exchange and the central control unit through internal connection units (IS1, IS2) and an internal connection control unit (ISt). The latter is actuated by a line address unit (AU) which also returns a calling signal to the subscriber lines.