| 摘要 |
PURPOSE:To interrput the busy circuit of a four-wire switch-board in both directions without lowering the call level, by coupling a four-wire/two-wire switching unit with an additional OD trunk device by actuating an operator panel controller by an interruption trunk. CONSTITUTION:When receiving a subscriber's number at the side of office A, originating register 9 actuates marker 10. This marker 10 makes sure that the A- office subscriber is busy from the B-office subscriber by way of additional OD trunk device 5, channel 4 and line circuit 7, and link 3 and additional OD trunk device 6. As a result, interruption trunk 11 is connected to line circuit 8 via link 2 and link 1 is released. This trunk 11 actuates operator panel controller 12 of the manual control part to couple four-wire/two-wire switching unit 13 with device 6 and then interrupts the busy circuit for the C-office circuit. Thus, the busy circuit of the four-wire switchboard can be interrupted in both directions without causing the call level to drop. |
