| 摘要 |
PURPOSE:To avoid useless repetition of call detection even when a processing- disabled state continues by providing a means for displaying the state of call processing unconsecution of a processing unit and a means for inverting the last look when the state is detected. CONSTITUTION:A line state detection circuit 1 scans a line L and records its state on a line state display circuit 2. The recording and the state of a last look holding circuit 3 are compared at a period of (c) in a figure. When the processing unit 5 is in the processing-disable state to a call detection signal at a point of time t1 in (d) in the figure, a flag display (f) is generated in a call delay flag 6 and a last loop inverting circuit 7 supervises it. That is, when a flag display exists at times T0, T1 during the supervised period of (g) in the figure, the stored content of the last loop holding circuit 3 is inverted as shown in the (b) in the figure. Then a dissidence detection circuit 4 gives a call detection signal to the processing unit 5 at a point of time t4. |
