| 摘要 |
PURPOSE:To evade a state getting weary of waiting for a long time holding, or consuming a wasteful time in uncomfortable feeling, by performing the recall of a telephone set performing a holding operation, based on the detection of a PB signal receiving means, by issuing a PB signal from a person to be held during the holding of a line. CONSTITUTION:At the time of arriving a call at a trunk line 16, an incoming call signal is detected at a central office line 6, and a central control unit 2 performs the display of the incoming call to an extension telephone set 1. By calling the extension telephone set 1, and receiving a response from the telephone set, the central office line 6 closes a loop, and a network switch 5 forms a channel (a). The trunk line is placed under a holding state until a desired opposite is found, and a call is received, but in such case, the channel of the network switch 5 is connected changing a connection from (a) to (b), or to (c). In case of requesting the discontinuance of the holding state by a caller, the PB button of its own telephone set is recommended to be depressed according to the recommendation of a message. The PB signal is inputted to a PB signal reception circuit 7 through the channel (c), and the extension telephone set 1 holding the trunk line is called by the action of the central control unit 14.
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