| 摘要 |
PURPOSE:To connect all external lines by an external line button even in a telephone set having less number of external buttons than number of external lines by making one of external line buttons to plural external lines. CONSTITUTION:When number of external line buttons of a pushbutton telephone set is in total M, (M-1) buttons are assigned individually to an external line and the remaining one is made correspondent to the remaining external lines. In this case, as to the external line button 107 corresponding individually to the external line, the corresponding external line is connected by depressing the corresponding external line button. On the other hand, depressing the external line button 108 of the remaining external line, an external line designation code is sent to a control section 207 of an exchange and a control section 207 retrieves automatically the external line not in use among the remaining external line group to apply the connection with the external line. Moreover, when an incoming call comes to the remaining external line, a lamp on the remaining external line correspondence button 108 is blinked and the incoming call is responded to by depressing the button 108.
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