Importance

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Abstract

A first ID code ESN (electronic serial number) for apparatus identification and a second ID code MIN (mobile identification number) such as a telephone number are stored beforehand in a non-volatile memory of a mobile telephone terminal. The mobile telephone terminal transmits these ID codes to a network at the time of communication, and whether or not this set of first and second ID codes has been registered is discriminated on the network side. Communication is allowed if the ID codes have been registered. In order to prevent unlawful use of the mobile telephone terminal in mobile communication, (1) the first ID code is encrypted on the side of a writing device and then inputted to the mobile telephone terminal when the first ID code is written in the non-volatile memory of the mobile telephone terminal, (2) the mobile telephone terminal writes the encrypted first ID code in the non-volatile memory as is, and (3) the encrypted first ID code is decoded at the time of communication and transmitted to the network along with the second ID code.

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First Claim