| 摘要 |
PURPOSE:To eliminate the need for the discrimination of the polarity of lines at the installation of the titled device, by monitoring a call signal for a prescribed time, if the inversion of the polarity of lines is detected at automatic dial call. CONSTITUTION:When an automatic call start is done with an automatic dial start section 1, an automatic dial control section 2 drives a line switching relay 3 and activates a polarity inversion detection section 11. In detecting the inversion of polarity, a drive relay of a call signal detection section 15 is operated, a call signal detection control timer 17 is operated, and the call signal is monitored for a prescribed time. When the section 2 discriminates the detection of the call signal, relay contacts 3', 3'' of the relay 3 are contacted, a relay contact 16' of a call signal detection drive relay 16 is opened to connect lines 7, 8 to an additional terminal 9. Then, the automatic dialing is inhibiting at the same time. |
