| 摘要 |
PURPOSE:To use only one pair of connection lead wires and to simplify a circuit by requesting a service request signal from the inside of a key telephone set to a telephone exchange through the same interface as a general telephone set. CONSTITUTION:The key telephone set 20 has function buttons 6 and is connected to the telephone exchange by using the same subscriber's circuit as the general telephone set as the interface. When various kinds of services are to be received during talking, the buttons 6 are pressed. The buttons 6 are provided with services such as ''holding'' and ''pickup''. When the button 6 is pressed, a microcomputer 22 detects the depression of the button 6. On the other hand, the telephone exchange is generally provided with various serivces, e.g. ''holding'' can be used by dialing ''hooking'', ''1'' and ''4''. |
