| 摘要 |
PURPOSE:To discriminate easily a telephone set having an incoming call with simple constitution by providing plural incoming tone generating circuits outputting different incoming tones and a memory storing in advance which incoming tone generating circuit is to be used to each telephone set and transmitting the different incoming tone depending on each telephone set to the telephone set. CONSTITUTION:Incoming tone generating circuits 4a, 4b, 4c used at each telephone set 6a, 6b are stored in a memory 2a and when a central processor 2 detects a cause to an incoming call, the memory 2a is retrieved based thereupon, which incoming tone generating circuits 4a, 4b, 4c are to be connected to which telephone sets 6a, 6b is decide and the processor 2 gives a command to a time division switch circuit 1 to connect them. Thus, the telephone sets 6a, 6b output different incoming tones from the incoming tone generating circuits 4a, 4b, 4c stored in the memory 2a in advance and even when lots of telephone sets are installed, the presence of an incoming call to a telephone set is recognized easily depending on the difference of the incoming tone.
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