| 摘要 |
PROBLEM TO BE SOLVED: To provide a new means for properly detecting hook information of an externally connected communications terminal, independently of the environment of the user. SOLUTION: A communication terminal apparatus is disclosed which includes a line voltage extracting diode bridge 1 connected in parallel with a public telephone line; upper limit and lower limit voltage detection circuits 3, 4 for comparing a line voltage extracted by the diode bridge 1 with first and second detection voltages respectively; and a control section 5. The control section 5 includes: a function of detecting the hook information of the externally connected communication terminal by receiving a comparison result by the upper limit and lower limit voltage detection circuits 3, 4; a function of correcting the first and second detection voltage so that comparison results by the upper limit and lower limit voltage detection circuits 3, 4 are coincident with each other when the comparison results by the upper limit and lower limit voltage detection circuits 3, 4 differ from each other; and a function of overwriting the comparison result information when the comparison results by the upper limit and lower limit voltage detection circuits 3, 4 are coincident with each other to data in a storage section 6 for the purpose of succeeding judgment of hook information. COPYRIGHT: (C)2007,JPO&INPIT
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