| 摘要 |
PURPOSE:To inform a terminal which is not communicating which terminal is communicating with a center at present by transmitting the response signal that is inherent to the terminal for a calling from the center through the center to other terminal. CONSTITUTION:By a polling system, a center 1 sends a calling signal 100 from a transmitting terminal S to terminals 21-2n through a communication line 3 successively. At this time, when the address terminal of the calling signal 100 receives the calling signal 100 from a receiving terminal R, it returns a response signal 200 inherent to the terminal from the transmitting terminal S to the terminal R in the center 1. The center 1 sends immediately this from the transmitting terminal S to other terminal through the communication line 3. When the other terminal receives the response signal 200 of the terminal which is during the communication from the receiving terminal R, it is specified from which terminal the signal is outputted. Thus, by receiving the response signal outputted by the terminal during the communication through the center 1, the terminal, which is not communicating, can recognize that it is presently communicating with the center 1.
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