| 摘要 |
PURPOSE:To control connection only with a PB signal which is an object and to remove erroneous actions caused by the PB signal except the object by discriminating the existence and the sorts of identifying elements supplied to the PB signal as for a control circuit and controlling the connection corresponding to the discriminated results. CONSTITUTION:A titled controller provides a used state storage means 200a which identifies to store the used state of an outgoing side which executes an outgoing call or an incoming side which has an incoming call every begining of a call, an identifying element giving means 200b which gives the identifying element to the PB signal corresponding to the used state stored in the used state storage means 200a when the PB signal is transmitted from a terminal in order to attain the control of the connection and circuits 25-27. By discriminating the existence and the sorts of the identifying elements supplied to the PB signal, the control of the connection can be executed corresponding to the discriminated results in a control circuit 200. Thus, an extension transfer with erroneous actions caused by the PB signal, transmitted from the telephone set of an opposite side, which can not be the object in substance can not be attained.
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