| 摘要 |
PURPOSE:To prevent the unnecessary continuance of line closing state by using an on/off-hook signal through a data communication line during the use of a pushbutton telephone set and using an output of a DC loop monitor section during the use of a conventional terminal equipment by an exchange so as to control the connection and opening of the circuit. CONSTITUTION:A pushbutton switch to switch the mode using a pushbutton telephone set 300 and the mode using a conventional terminal device 401 to be connected is provided, and a signal representing the mode is sent from an electronic exchange 100 through a data communication line every changeover of the mode. On the other hand, the exchange 100 monitors the signal from the telephone set 300 at all times. During the use of telephone set 300, the on/off- hook signal given through a data communication line 201 is used and during the use of the conventional terminal device 401, a monitor output from a DC loop monitor section 107 is used to apply line connection and line open processing. Thus, the continuance of the line closing state is eliminated.
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