Telephone patching apparatus

Abstract

For use in telephone answering service installations, a circuit device is disclosed for bridging or patching external calls, such as an incoming call to a dialed-out call, and for timing the duration of (actual time usage of) the interconnection. The device is adapted for providing a coupling between a pair of the telephone front cord plugs of a conventional PBX switchboard. Circuitry is provided for sensing the mechanical connection of a jack to a plug and for sensing electrically the completion of the telephone call connection, for inductively coupling incoming and outgoing calls, for automatically disconnecting the inductive coupling upon sensing termination of a call connection and for timing, displaying and at least temporarily storing the duration of the call interconnection for entering a time charge to the customer's account. In the preferred embodiment, light emitting diodes (LEDs) coupled in series with the telephone lines are operative to trigger a photosensitive logic switch optically isolated from the phone lines, which switch operates logic control circuitry. The logic control circuitry initiates and terminates call timing circuitry and controls relay switching circuitry for automatically disconnecting the bridged telephone lines only upon the actual interruption of a call connection. The disclosed circuit is relatively immune to transients which would otherwise cause call interruption. Further, the call timing circuitry includes provision for automatic display of an initial billing unit and for selection of the duration of the base billing unit of each subscribing customer.

Dependencies are inferred from the claim text.