| 摘要 |
PURPOSE:To attain sure morning call by increasing the call tone volume gradually in response to the number of times of no reply so as to attain redialing. CONSTITUTION:In designation the time by an extension subscriber telephone set 2, it is stored correspondingly in a memory 6 for each LEN (Line Equipment Number) No. Then the stored time is detected by a clock circuit 7 to call an extension subscriber telephone set 2 by a ringing trunk (RGT) 4, it is informed by sound, while a timer 8 is operated to monitor the hook-off of the subscriber line telephone set 2. Then if a prescribed time passes without hook-off, timeout takes place and the timer 8 is operated again while increasing the call tone volume to monitor the hook-off, and if the extension subscriber telephone set 2 hooks off, the storage of the corresponding LEN No. in the memory 6 is released. Thus, the sure morning call is attained.
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