| 摘要 |
PROBLEM TO BE SOLVED: To prevent the ringing of call sound and a unnecessary call at a specified place without depending on the consciousness of a user carrying a radio terminal by receiving a down control channel signal, inverting the phase and transmitting it to the radio terminal within a specified space area and time with a frequency similar to that of the down control channel signal. SOLUTION: A down channel reception part 2 receives the down control channel signal transmitted from a radio base station and repeats the down control channel signal to a phase inversion part 3 and a control part 6. The phase inversion part 3 inverts the phase of the received control channel signal and repeats it to a down channel transmission part 4. The down channel transmission part 4 transmits the down control channel signal whose phase is inverted with the frequency similar to that of the down control channel signal transmitted from the radio base station. Thus, the call of the radio terminal and origination from the radio terminal with specified/limited space are disabled without changing the radio terminal-side with such constitution.
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