| 摘要 |
PURPOSE:To obtain a small and economical line circuit, by setting a line circuit line concentrator between a subscriber terminal and a time division switch. CONSTITUTION:The calling state of a subscriber 1 is monitored by a local processor 8 via a line circuit 7. When the processor detects the off-hook of the subscriber 1, the circuit 7 is cut off and the subscriber 1 is connected to an idle line circuit 10 via a line circuit concentrator 9. With the on-hook of the subscriber 1, the subscriber 1 is cut off from the circuit 10. Then the subscriber 1 is connected to the circuit 7. When the subscriber 1 has an incoming, the called subscriber 1 is first connected to a test trunk 11 via the concentrator 9 and under the control of the processor 8. The trunk 11 performs a test of the subscriber line. If a satisfactory result is obtained from the test, the called subscriber 1 is connected to the circuit 10 through the concentrator 9. Then a call signal is sent to the called subscriber 1. The procedure from the answering to the on-hook is identical with the conventional one. |
