Dual line adapter for telephone answering machine

Claim 1

An adapter circuit and system for coupling a telephone answering machine to first and second telephone lines, said telephone answering machine including a coupling circuit for transmitting audio signals between the first and second telephone lines and the telephone answering machine, and a line seizure relay circuit included in said coupling circuit responsive to a line seize signal from the telephone answering machine for connecting the coupling circuit to the first and second telephone lines, said adapter circuit and system including: a first input circuit adapted to be connected to the first telephone line for producing a first output signal in response to a first ring signal received thereby over the first telephone line; a second input circuit adapted to be connected to the second telephone line for producing a second output signal in response to a second ring signal received thereby over the second telephone line; first switching means connected to the first input circuit and responsive to said first output signal for enabling said first input circuit to introduce the first ring signal received thereby to the telephone answering machine; second switching means connected to the second input circuit and responsive to said second output signal for enabling said second input circuit to introduce the second ring signal received thereby to the telephone answering machine; first latching circuit responsive to said line seizure signal from the telephone answering machine to latch said first switching means closed following the occurrence of the first output signal; a second latching circuit responsive to said line seizure signal from the telephone answering machine to latch said second switching means closed following the occurrence of the second output signal; and disabling circuitry interconnecting said first and second input circuits to prevent the closure of either one of said switching means when the other has been latched closed.