| 摘要 |
PURPOSE:To make a state that a subscriber's line is seen from a high-order switchboard coincide with a state of a slave station side by utilizing effectively a radio circuit by cutting off temporarily the radio circuit when the higher rank switchboard side executes an on-hook first after a cell is ended, and opening a DC loop by opening a terminal circuit in a line concentrator at the time of an on-hook of the slave station side. CONSTITUTION:After a call of a subscriber 5 and 6 is added, when the former executes an on-hook first, a line concentrator 2 controls a base station 3 and cuts off a radio circuit to a slave station 4 by detecting a busy tone (BT) sent out of a switchboard 1 by a detector 28, also terminates a subscriber's line by a terminating circuit 24 by driving switching circuits 22, 23 of a subscriber's circuit 15, and holds a DC loop to the switchboard. The slave station sees a cutoff of the radio circuit, cuts off the radio circuit by itself, too, generates a BT in the inside of the own station, and informs an on- hook to a telephone set. When the subscriber 6 executes an on-hook in accordance with said state, the radio circuit is formed again, and the on-hook is informed to the line concentrator. As a result, the line concentrator operates the switching circuit, and opens the DC loop to the switchboard by separating the terminating circuit 24 from the subscriber's line. |
