JPS6419895A - Key telephone system - Google Patents

Abstract

PURPOSE:To inform the operating method of a key telephone system to a user at the service interruption by securing such a constitution where a 1st control means turns on a message production means when an energized state is changed to a service interruption state and at the same time connects the voice output line of said message production means to each terminal of the key telephone system to turn on a loudspeaking circuit of each terminal. CONSTITUTION:When a service interruption occurs to a key telephone system, a service interruption detecting circuit 9 detects the service interruption. This detection signal is fetched by the input/output processing. Then a control circuit 8 closes the contact of a cross point and sets the data at an output buffer 50 to secure the connection of extensions between the key telephone sets 21-2m and a tape recorder 4. Then the circuit 8 set a timer at a prescribed time for start of clocking. Thus the tape recorder 4 starts and the sound signals are sent to the sets 21-2m to explain how to operate the key telephone system. When the timer counts up the prescribed time, the contact of the point 6 is released. As a result, the operating method is automatically informed to users via a loudspeaking circuit from each of the telephone sets 21-2m when the telephone system is set in a service interruption state from an energized state.