| 摘要 |
PROBLEM TO BE SOLVED: To provide a portable telephone system by which a user can know that a user enters a weak electric field area beforehand without any interruption of conversation by notifying the user about that an electric field becomes weak by a tone. SOLUTION: A control part 12 decides the level of a ratio wave received from a radio part 11 and outputs a voice message other than a voices of conversation to a loudspeaker 13 in accordance with the decided results.
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