Bell Telephone Laboratories

Wayne Jay Egan

Steven Gary Miller

Richard Henry Bidlack

Alan M Gordon

Ronald Joseph Angner

William Andrew Huryn

There is disclosed a protective coupler for use with key telephone line units (KTU) to provide isolation between the terminal equipment and the central office line. The protective coupler plugs onto the KTU option socket and establishes a dielectric barrier to protect the system from possible overvoltages, guarantees a balanced termination, and meets leakage requirements while remaining operable to pass control and voice signals between the network and station equipment. The central office side of the barrier contains a current sink for control purposes as well as a gain compensation circuit to adjust for varying distances from the central office.

Key telephone unit protective coupler

A key telephone system signal priority arrangement is disclosed wherein each type of call in a key telephone system is assigned a distinctive priority. When a call is directed to a station engaged in an existing lower priority call, a warning tone is given to both parties engaged in this existing call. The existing call is then automatically placed on hold while the preempting call is completed to the called station such that the called station can answer the preempting call 'hands-free'.

Key telephone system signal priority arrangement

A key telephone system is disclosed in which a direct station selection (DSS) arrangement reduces the number of operations required for the attendant to extend an incoming central office call to a station. The operation of one or more DSS keys on any of the attendant consoles in the key telephone system automatically places the calling central office line on hold and establishes a communication path through the DSS key contacts from the attendant to the selected station. DC bias on this communication path activates a loudspeaker and microphone arrangement in the selected station so the called party may converse with the attendant 'hands-free.' Additionally, the DSS arrangement provides the capability of utilizing any station in the key telephone system as the attendant position.

Direct station selection hold arrangement

A key telephone system is disclosed in which intercom calls may be answered 'hands-free' at the called station. Intercom calls are originated in the standard manner, with the subscriber picking up the handset at the calling station and dialing the number of the called station. A voice communication path is established through the station selector to the telephone set represented by the dialed number. DC bias on this communication path through the station selector activates a loudspeaker and microphone arrangement in the called telephone set. The called party may thus converse 'hands-free' with the calling party by utilizing the activated loudspeaker and microphone of the station set, and need not manipulate the station set for the duration of the conversation.

Growing community of inventors

Eatontown, NJ, United States of America

Wayne Jay Egan