| 摘要 |
PURPOSE:To simplify the constitution of the transmitting part by transmitting the data signal and the sound signal between the master equipment and the terminal telephone set at the base band area and by the time base system. CONSTITUTION:When an incoming detecting circuit 20 detects the line wire incoming in a master equipment 1, a CPU 17 sends the line wire incoming signal through serial data I/F 22 to signal lines L3 and L4. Thereafter, the CPU 17 sends the line wire incoming sound to the signal lines L3 and L4 while the CPU 17 drives a sound source 18. When the hand set of a terminal telephone set 2 is raised, a CPU 9 detects the line wire response, and the base band data are transmitted to the master equipment 1 by the base band data. When the line wire calling is executed during the extension call, the master equipment 1 injects forcibly the line wire calling pulse to the signal lines L3 and L4 during the extension call, changes over relays Ry1 and Ry2 of a terminal telephone set 2 to the line wire calling condition and transmits the line wire calling signal from the master equipment 1.
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