| 摘要 |
PROBLEM TO BE SOLVED: To ensure security of data by not accessing data specific to a possessor of a card before replacement when a card after replacement is loaded in the case that the card mounted to a telephone set main body is replaced during momentary interruption of power supply. SOLUTION: On the occurrence of momentary interruption of power supply, (S150 YES, S160: YES), an IC card 5 mounted when a power supply is restored after the occurrence of momentary interruption of power supply is the same as before the occurrence of momentary interruption of power supply as a condition of executing continuously the operation (S140) similarly the state of the occurrence of momentary interruption of power supply. That is, manufacturing numbers of the IC card are compared and whether or not they are the same is discriminated. In the case that the IC card is replaced, data stored in a storage section are masked or deleted (S190). For example, there are a message or mail data addressed to a preceding user, they are masked. Thus, data with high privacy are protected from other party and the security is ensured. |
