Communications system using portable recording medium

A communications apparatus comprising:

• a card in which a first card ID is stored;
• a card detecting section for detecting insertion of the card;
• a power switch for turning on and off the power;
• a card ID storing section for storing a second card ID even when the power switch is in an off state;
• a card ID judging section for comparing the first card ID stored in the card and the second card ID stored in the card ID storing section;
• a dialing section for enabling a dial input;
• a local authenticating section provided in the card for collating a code number that is input through the dialing section and a code number stored in the local authenticating section;
• a center authenticating section provided in the card for performing a center authentication operation with a center apparatus connected to the communications apparatus via a communications network;
• and
• a control section for managing identification of the card;
• wherein when the card is inserted during an on state of the power switch or when the power switch is turned on after the card is inserted during an off state of the power switch and the local authenticating section determines that the code number stored therein and the code number input through the dialing section are identical, the control section reads the first card ID from the card and the judging section compares the first card ID and the second card ID, whereby the control section does not execute an authentication operation when the judging section determines that the first card ID and second card ID are identical, and whereby the control section calls a center apparatus through the dialing section, performs the authentication operation with the center apparatus, and stores the first card ID into the card ID storing section when the judging section determines that the first card ID and second card ID are not identical.