| 摘要 |
PURPOSE:To eliminate the need for a changeover of a tone/pulse selector switch to the position of the tone at each time by providing a polarity inversion detector and using polarity inversion information outputted from the polarity inversion detector. CONSTITUTION:A series of a dial number is sent to a station exchange as a dialing, and when the opposite party replies, the polarity of its own station is inverted. When the polarity inversion detector 11 detects the polarity inversion and outputs polarity information '2' to a tone pulse changeover controller 12, then the tone/pulse changeover controller 12 outputs logic 1. Then after dialing, the reply of opposite party and the inversion of polarity, when a dialer 8 detects a key input, since an input logic of a tone/pulse changeover input terminal 8a is logical 1 even when the tone/pulse changeover switch 7 is turned to the position of the pulse side, a pushbutton dial signal is sent to a line. Thus, it is not required to switch the switch to the position of the tone at each time.
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