INTERFACE UNIT FOR COUPLING SEVERAL MICROPHONE/LOUDSPEAKER DEVICES TO A TELEPHONE TERMINAL

摘要

A telephone interface unit for coupling a handset (1) and an all-in-the-ear type device (2) to a telephone terminal (10) having access to a single telephone channel. The interface unit has a comparator (5) for comparing signals generated by the microphones of the handset and the all-in-the-ear device and for generating a control signal (8) identifying which is the largest. This control signal (8) provides switching input to a switch means (4) which selectively couples that one of the handset and the all-in-the-ear device generating the largest microphone signal to the telephone terminal (10).