| 摘要 |
PROBLEM TO BE SOLVED: To allow a portable telephone set to easily lock/release the dial and to prevent a lost portable telephone set whose locking is released from being used by a 3rd party. SOLUTION: A lock release code transmission section 22 built in a lock release device 20 sends a radio wave with a lock release code superimposed thereon and a lock release code reception section 12 of a portable telephone set 10 receives the radio wave and collates the code with a code stored in advance in a control section 11 and dial locking is released when they are coincident. Furthermore, when the code is not received for a prescribed time in this state (in the case where the lock release device is disconnected), dial locking is applied again. Moreover, an output of a transmission section is adjusted so that a radio wave arrival distance to the reception section of the portable telephone set is within 1 to 2m.
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