| 摘要 |
PURPOSE:To eliminate the need of a complicated operation and to automatically execute privacy communication or ordinary communication by transmitting a discrimination code whether or not there is a privacy telephone system in an opposite station from an originating station side and deciding whether or not a response from the opposite station is executed in a specified period. CONSTITUTION:The ID code for the discrimination of a terminal is transmitted from the code generating device 2 of the privacy telephone system 1 of a set A after completing connection and the response from the system B is monitored by a timer 9. When the response is not sent in a certain period, the system A side decides that there is not privacy telephone system in system set B and switches analog switches 3 and 4 to the ordinary communication side so as to execute the ordinary communication. In the communication between the system A and a system C having the privacy telephone system 5, the IC code is received by the code receiver 6 of the system C so as to directly retransmit an ID code reception code. The IC code reception code is detected in a code receiver on the system A side and switches 3 and 4 are switched in a privacy communication mode so as to begin the privacy communication. Thus, the ordinary communication and the privacy communication can be automatically switched without necessitating the complicated operation.
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