Abstract: Calls redirected off-net, which includes call forwarding and call coverage, is provided at the switch to which the call is initially directed (the principal party's switch), by monitoring the redirected off-net connection with a call classifier and listening for the appearance of ringback tone and the appearance of voice frequency energy. The call is allowed to be completed to the off-net covering end-point if voice frequency energy is detected before ringback tone appears or if voice frequency energy appears within a predetermined time-out interval. If ringback tone continues beyond a time-out interval, if voice-frequency energy is not detected within the time-out interval, or if a call progress tone other than ringback is detected, further processing of the call is continued at the principal party's switch to determine if another covering point is listed. If no other coverage point is listed, monitoring of the call continues until the calling party hangs up.

Abstract: In a private branch exchange apparatus having a plurality of extension ports, each extension port capable of connecting a push button telephone and a general standard type telephone in parallel, when a call occurs at one extension port where the parallel connection has been done, a ring sound can be produced at the push button or standard type telephone selectively. An additional dialling provides the selection between the push button and the standard type telephone. A memory may specify either of the push button or standard type telephone to be ringed. A call between the push button telephone and the standard type telephone can be provided in accordance with the additional dialing or data stored in a memory.

Abstract: A telephone subscriber interface device provides privacy on a party line. The device provides for revertive calling, break-in, automatic disconnect, selective ringing, automatic number identification, and operates on the central office power supply. The device provides the following features: A connect state for the PLC in which the PLC is connected to the telephone line but in which the PLC is not responsive to other inputs, a ring decoder which detects either divided coded ringing signals or divided ringing signals in a novel manner, means for testing whether a revertive call has been properly terminated, a low power switch so that the PLC can run on telephone line power only without battery backup, and means for resetting the PLC to a ready state in the absence of other inputs.

Abstract: A telephone security clamp for preventing removal of modular telephone equipment which is electrically connected by its modular jack to a modular socket. The security clamp includes a wedge which is inserted beneath the release tang of the modular jack. The tang is thereby blocked and prevented from being depressed to thereby prevent removal of the jack from the socket. A housing clamps the wire directly adjacent the wedge and thereby prevents access to the wedge. The wedge and housing can be integrally formed of unitary construction.