| 摘要 |
PROBLEM TO BE SOLVED: To provide an apparatus and method for detecting and controlling a telephone line state in which busy tones are sent to a telephone set when dialing operation from the telephone set to a telephone line network is performed while a telephone line is unconnected. SOLUTION: The apparatus, to which a telephone line network 30, a leased communication line network 20 and a telephone set 40 are connected, performs dialing operation to an opposite side telephone set 60 in place of the telephone set 40 and includes: an open polarity detection section 10e for detecting an unconnected state where the opposite side telephone set 60 is not connected to a telephone line LX2 constituted of two lines LX2n, LX2r and potentials of both the two lines LX2n, LX2r are high, a polarity non-inverted state where there is no call arrival/origination at/to the telephone line LX2 and a potential of one line LX2n of the two lines is high, and a polarity inverted state where a potential of another line LX2r of the two lines is high; and a control section 10a which controls connection of the telephone set 40 and the telephone line LX2 and the dialing operation. COPYRIGHT: (C)2006,JPO&NCIPI
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