| 摘要 |
PURPOSE:To enable economical subscriber monitor, by transmitting the monitor information to the subscriber circuit through the use of the same selection circuit even after the subscriber circuit having monitor function of subscriber state has been changed over from the subscriber. CONSTITUTION:Since the common control unit 9 delivers howler tone to the subscriber 1 in the subscriber lockout state, the contact t in the subscriber circuit is closed. The test link 5 is closed and the subscriber 1 and the howler tone delivery trunk 6 are connected. The howler tone is delivered to the subscriber 1 from the sound source 7 via the test trunk 5 and contact t. When the subscriber 1 is OFF- hook, the relay A in the howler tone delivery trunk 6 is operative via the contact t and reaches the monitor circuit 3 of the subscriber circuit 2. That is, the common control unit 9 can receive the OFF-hook information of the subscriber 1 from the monitor circuit 3 even after the selection of the subscriber circuit via the scanning unit 8. |
