| 摘要 |
PURPOSE:To grasp the use condition of a service by not using a control line (C line) of an intra-office exchange to count the number of incoming calls of the telephone service by the first timer circuit. CONSTITUTION:+12V is supplied to the first timer circuit 15 from a transistor TR 9 by closing of a contact r3 to generate a +12V pulse of 0.5sec, and a TR 13 is operated through a rectifier 18 and a protective resistance 14 to operate an incoming call number counter 12. Further, the second timer circuit 16 is started by opening of a contact r4. An optional operation time is set preliminarily to the second timer circuit 16; and when this time elapses, a circuit opening B relay 17 is operated, and a holding circuit of a trunk line monitor R relay 19 is disconnected by the operation of a contact b23 of said relay 17 to open the line.
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