| 摘要 |
<P>PROBLEM TO BE SOLVED: To achieve a communication terminal device compatible with dial-in services, capable of preventing malfunction by correctly deciding polarity of a trunk line. Ž<P>SOLUTION: The communication terminal device with a dial-in connection function of a push button signal system includes: a polarity determining function for determining the polarity of a trunk line; a temporary response signal transmission function (S406) for transmitting a temporary response signal to a line in response to the reception of a calling function after the polarity determining function detects the inversion of the polarity of the trunk line; an extension line designating signal detecting function (S408) for detecting the reception of an extension line designating signal from an exchange after the temporary response signal is transmitted from the temporary response signal transmitting function; and a polarity deciding function (S410) for deciding the polarity of the trunk line by the polarity determining function in response to the detection of the reception of the extension designating signal by the extension line designating signal detecting function. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
|
