Line switching circuit for cordless telephone
September 18, 2006. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesInterconnect control for automatically connecting a simplex or half-duplex radio network to a standard telephone system Speakerphone for radio and, landline telephones Portable radio telephone Subscriber telephone station Telecommunications systems Portable cordless telephone transceiver-radio receiver Cordless telephone Telephone interrupter Patent #: 4640988 InventorApplicationNo. 06/908573 filed on 09/18/1986US Classes:455/417, Call diversion455/462, Including private cordless extension system455/553.1Radiotelephone having plural transceivers (e.g., for analog and digital, trunking and cellular, etc.)ExaminersPrimary: Lev, RobertAttorney, Agent or FirmInternational ClassesH04M 1/72 (20060101)H04M 1/725 (20060101) Foreign Application Priority Data1985-09-30 JPAbstractA line switching circuit for a communications system which includes a cordless telephone and gives priority of use to an ordinary telephone associated with the cordless one is disclosed. The circuit includes a current detector for detecting a current which flows through the telephone, a circuit having a time constant on only one of positive going edges and negative going edges of an output of the current detector, a relay interposed between the cordless telephone and a subscriber's telephone line, and a driver for driving the relay. The relay is closed immediately upon change of the telephone from an off-hook state to an on-hook state and opened with a predetermined time constant upon change of the same from an on-hook state to an off-hook state, whereby a hand-over of conversation between the telephones may be effected without any malfunction even if a ringing signal from a central office is received. | |
