| 摘要 |
PROBLEM TO BE SOLVED: To save power of a telephone system by providing a central control part which instructs a power supply part to switch the terminal supply voltage from the waiting voltage to the call communication voltage, when a terminal is shifted to a calling state from a waiting state. SOLUTION: When the calling signal detection monitoring processing of a telephone system 1 is started, a central control part 12 monitors a calling signal. A waiting state set under such conditions means that a terminal 2 connected to the system 1 is kept in an on-hook state. When the calling signal sent from the terminal 2 is detected and the waiting state is shifted to an under- communication state by the fact that an answer signal is received from an arriving side terminal, the part 12 instructs a power supply part 13 for switching the terminal supply voltage from the waiting voltage to the call communication voltage. Then the part 12 monitors the cutoff signal received from the terminal 2 in a communication state. When a cutoff signal received from the terminal 2 is detected and a waiting state is set, the part 12 instructs the part 13 to switch the supply voltage to the waiting voltage. The system 1 having the terminal 2 set in an on-hook state carries on its processing. |
