Siemens-albis, Ag

Gunther Weisigk

Eugen Rippstein

Karlheinz Schmah

Eugen Musterle

Harald Berger

Subscriber stations in a telecommunication system are selectively connected and controlled by an exchange having a central control. The subscriber stations have operating conditions varying from an idle to a start condition and from a captive to the idle condition. Line connection circuits of the subscriber stations issue a signal indicative of a transfer of any subscriber station from the captive to the idle condition. Circuits common to the subscriber stations but separate from the central control monitor the subscriber stations as to the issuance of a signal indicative of a transfer of a subscriber station from the captive to the idle condition. Circuit components common to the subscriber stations and connected to the monitor circuits ascertain the particular subscriber station for which an indicative signal has been issued and carry out a release of the particular captive condition. The monitor circuit preferably monitors the subscriber stations also for a transfer from the idle to the start condition, and the system preferably is capable of issuing a corresponding request for a connection to the central control. The subscriber stations preferably are divided into groups for joint interrogation of transfer conditions, and may be subdivided into subgroups for individual interrogation of transfer conditions among the subscriber stations of a subgroup.

Telecommunication systems with captive condition surveillance and release

Apparatus is disclosed for feeding ringing currents from a ringing current supply to line circuits, and for controlling ringing currents in such line circuits, in telephone and other telecommunication systems having an exchange equipped with a source of supply voltage and having subscriber circuits equipped with a ringing circuit capacitor. The disclosed invention comprises a combination of a junction for feeding ringing currents to line circuits, a diode connected between the feeding junction and a pole of the source of supply voltage, an electronic switching device having a control electrode and being connected between the ringing current supply and the feeding junction, and equipment connected to the control electrode of the switching device for causing the switching device to switch ringing currents on and off instantly and to discharge the ringing circuit capacitor.

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Zurich, Switzerland

Gunther Weisigk