| 摘要 |
PURPOSE:To improve the efficiency of utilization of trunk lines or a switchboard by performing non-answer monitoring by an incoming-side switchboard to a proper time limit which corresponds to the kind of a called subscriber. CONSTITUTION:On calling a called subscriber B, an incoming-side switchboard BX starts non-answer monitoring to a time limit which corresponds to the called subscriber B. At the said time limit without the called subscriber B answering, a central controller CC operates the relay X of an incoming trunk ICT for a certain time through a relay driver RC to intermit a DC supply circuit to a trunk line T through a relay A2. During this period, a relay in operation is released in an outgoing trunk OGT. The central controller CC of an outgoing-side switchboard AX monitors the operation of the relay L of the OGT by a scanning point 3 through a scanner SCN. On detecting the intermit release of the relay L, the central controller CC performs called-subscriber non-answer processing. |
