| 摘要 |
PURPOSE:To call user's attention to permanent call by outputting a howler tone with high sound volume in a telephone set circuit. CONSTITUTION:A howler signal transmitted from an exchange to terminals L1, L2 is converted into a DC and applied to a call circuit RG. Since the call circuit RG generates a signal in 1,000Hz at the same way as the arrival of a call signal and raises a ring of a calling acoustic device SD, the howler tone with a high sound volume calling sufficiently the user's attention is outputted. |
