| 摘要 |
PURPOSE:To allow a communication line a common use with a calling and discrimination signal transmission by using a multi-frequency signal made of audible frequencies instead of dial pulses as a call location discrimination signal for an emergency telephone set. CONSTITUTION:The telephone set parts 11 of the plural emergency telephone sets 10 are connected in multiple connection, and are connected to the telephone set part of an attendant board 30 through the two way communication line 40, the exchange circuit part 21 of an exchange 20, and a communication line 41, and function as a telephone set. A location signal transmission part 12 transmits to the communication line 40 through the telephone set part 11 a numerical code given to each emergency telephone set 10 by means of the combination of prescribed audible frequencies. A call location discrimination part 22 receives the audible frequencies as a location signal from the location signal transmission part 12, and discriminates the number of the emergency telephone set at the transmission source i.e. the call location, then outputs it through a location signal line 42, so that it is displayed in the call location display part of the attendant board 30.
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