Telecommunication system with gateway speech terminal

摘要

The gateway speech terminal has an amplifier circuit (VS) connected to an external voltage source (SQ) and switched on when required as a result of events occurring on the connection lines (ASL). The events are overlapping ac voltages and/or changes in the dc component due to speech transmission or activation of an external key (TA). An indicator is coupled to the connection lines to switch the supply of the amplifier in response of the detected event. The switching on of the amplifier circuit for a specific period of time does not require extra control lines between the gateway speech terminal and the system. Control signals are sent from a CPU to a terminal.