| 摘要 |
PURPOSE:To improve the processing performance of the two-party subscriber discrimination system of a telephone switchboard, by performing the discrimination in a short time by detecting electric currents flowing through subscriber's lines A and B, and then by performing loop monitoring by the sum of current values and two- party discrimination by the difference. CONSTITUTION:Once a subscriber calls, the A-line current of subscriber's telephone set 301 and subscriber's line 302 flows to office power source 303, and its return- circuit current flows through line B. Those A-line and B-line currents are detected by detecting circuits 304 and 305, adding circuit 308 obtains the sum of the both, and detecting circuit 310 for subscriber's line loop monitoring monitors calling information. If the subscriber is the party A-subscriber, the output of subtracting circuit 309 which subtracts the B-line current value from the A-line current value increases, so that the party A-subscriber can be discriminated. On the other hand, when the party B-subscriber, the output of subtracting circuit 309 decreases, so that the party B-subscriber can be found. |
