an improved telephone test unit is disclosed which permits the telephone line technician to selectively choose the audio reproduction of signals ocurring on the line without the use of the handset in the test unit . an auxiliary amplifier is provided to amplify the signals which are received from the telphone line . when the amplifier is activated , the transmitting unit and receiving unit of the handset within the telephone test unit are electronically muted to prevent undesirable audio feedback to the amplifier . the gain of the amplifier may be selectively varied between an off , low and a high gain condition . the amplifier is also usable in the &# 34 ; monitor &# 34 ; condition of the telephone test unit .