Abstract: 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.