| 摘要 |
PROBLEM TO BE SOLVED: To accurately transmit a line wire telephone number signal to a public line, without being affected by surrounding noise of a radio portable set in the case that a line controller transmits the line wire telephone number signal received from the radio portable set to the public line through a voice line as a pushbutton PB signal. SOLUTION: In response to a radio portable set transmitting a line wire connection request signal (e.g. '0'), a line controller makes dial connection to a public line, the line controller transmits a reception tone signal to the radio portable set via the public line in dial connection, and the line controller transmits the line wire telephone number signal that is transmitted by the radio portable set receiving the reception tone signal to the public line. In this case, a unidirectional voice line from the line controller to the radio portable set is set up, and the reception tone signal is transmitted to the radio portable set, the voice line is maintained till at least the transmission of the line wire telephone number signal by the radio portable set is finished and, for example, when a line wire telephone set is hooked off, the voice line is switched to be a two-way line. |
