| 摘要 |
PURPOSE:To stop the transmission of a tone signal to a calling telephone set and allow the calling telephone set to confirm the on-hook state of a called telephone set by entering an extension individual voice calling state automatically when the called telephone set engaged with a telephone set enters the on-hook state. CONSTITUTION:The exchange EX corresponding to the processor of the main device of a key telephone set is equipped with trunk lines CO1-CO5 and telephone sets ST1-ST16. Further, output lines of hook switches HS<2> of the telephone sets ST1-ST16 and control lines for switch circuits SW1 of the telephone sets ST1-ST16 are connected to a detection part OHD and a control part CT corresponding to the processor. The detection part OHD detects the on-hook state of a telephone set engaged with the extension link in the exchange or one of the trunk lines CO1-CO5. The control part CT is actuated by its detection output to control a circuit TSG, and the transmission of the tone signal to the calling telephone set is stopped to facilitate the confirmation of the on-hook state of the called telephone set. |
