| 摘要 |
<p>1. A telephone set comprising a low output voltage transmitter (2) and a receiver (3) disposed in a hand set (1) connected by a four wire flex (5, 6, 7, 8) to a case (4) comprising supply means (11) and line connection means (10), the hand set also comprising a pre amplifier (12) amplifying the output signal of the transmitter (2) and connected to the supply means (11) by a first (5) and a second (6) conducting wire, the output signal of the pre amplifier being transmitted by the same conducting wires (5, 6) to the case (4), characterized in that it comprises a switch (20) disposed in the hand set for interrupting the transmission of signals by the pre amplifier (12), and signalling means responsive to the position of this switch for producing a signal perceptible by the user when this transmission is interrupted.</p> |
