| 摘要 |
PURPOSE:To enable a simple device to transmit a call signal in incoming connection by monitoring intermittent call signals, shifting in phase, at any time and by selectively controlling a call signal transmitted at the point in time of the incoming connection. CONSTITUTION:As an incoming request arrives at one of subscribers 10-1n, central controller 4 controls exchange switch 5 to set the channel between the subscriber or trunk having received the incoming request and incoming subscribers 10-1n and, at the same time, sends the indication of call signal transmission to corresponding one of line circuits 20-2n. Call signal generator 3 generates intermittent call signal shifting in phase and one of them is connected invariably. Central monitor device 4 receives information on the call signals from memory device 6 monitoring and storing the said call signals all the time and then sends to line circuits 20-2n the indication of the connection of the call signal having the connection phase at this point in time. |
