| 摘要 |
PROBLEM TO BE SOLVED: To provide a portable telephone set that is sufficiently utilized by the user by providing much more opportunities of use of the portable telephone set to the user, though there are the problems that the user can not sufficiently utilize a conventional portable telephone set. SOLUTION: A comparator 1 discriminates to be outside of zone/inside of zone based on a reception electric field strength detected by a reception section 6 and on number of errors in digital data detected by a decoding section 8, and when a CPU 11 discriminates that the portable telephone set moves from a service zone to an outside of zone, the CPU 11 starts to operate a timer 15 which starts counting a prescribed time and the CPU 11 allows a display section 14 to make a proximity indication that displays that the portable telephone set existed in an inside of zone just before till the timer 15 was in time out.
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