| 摘要 |
PURPOSE:To detect a MF signal as a sent dial signal even when the MF signal is inputted directly from the transmitter of a key telephone set by providing a MF signal monitoring means which monitors the transmission of the MF signal sent out to a connection line. CONSTITUTION:The MF signal monitoring part 31 is provided which monitors the transmission of the MF signal from the connection line. When the line is connected to an exchange 20, the MF signal corresponding to, for example, a dial number '0' is inputted from the transmitter of the key telephone set 10 through, for example, an acoustic coupler and then the MF signal of '0' is sent out to the connection line of an exchange 20 through a line connection part 32. At this time, the FM signal monitoring part 31 detects the MF signal of '0' sent out to the connection line and informs a control part 33 of it. The control part 33 discriminated whether or not the origination of the key telephone set 10 sending out the '0' MF signal is controlled or not and controls a line connection part 32 so as to disconnect the line between the key telephone set 10 and exchange 20.
|
