| 摘要 |
PROBLEM TO BE SOLVED: To obtain a message device which can find erroneous setting in its early stage even when the telephone number of a message destination is erroneously set to the message device by deciding that a telephone number except a prescribed message destination is set when a response signal is not received within a prescribed time after confirming line connection. SOLUTION: When a message device 1 sets the telephone number of a third person except a security center device 2 to a 1st telephone number, the device 1 first calls to the telephone system 6 of the third person. However, even if the system 6 of the third person responds to a calling signal and an exchange 3 inverts the polarity of a telephone line 4 and detects it, naturally, a response signal from the device 2 is never received. Then, when a prescribed response signal is not received after polarity inversion detection, the device 1 decides that a storing part stores the telephone number of a third person except a security center mistakenly as calling to the system 6 of the third person except the security center.
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