Abstract: A security system capable of safely performing home device state check or operation. In the security system, a mobile telephone module of a mobile telephone transmits M-series data (call signal) to home device modules provided in home devices such as a door lock and home electric appliances. In response to this call, the home device module returns a home device ID to the mobile telephone module. The mobile telephone module authenticates the home device module according to the home device ID and after authentication, returns a mobile telephone ID and state check or operation command to the home device module. The home device module authenticates the mobile telephone module according to the mobile telephone ID. When this mutual authentication is complete, the home device module performs the home device state check or operation according to the command and returns the result to the mobile telephone module.

Abstract: The present invention provides an authentication card inserted to a portable device. The authentication card 1 is inserted (installed) in a cellular phone 30 and the authentication card 2 is inserted (installed) in a PDA 40. The authentication card 1 comprises an identification code transmission unit 10 and the authentication card 2 comprises a usage restriction cancellation unit 20. The units 10 and 20 exchange the identification code by means of wireless signal and mutually authenticate the identification code mutually. In case that the PDA 40 is moved more than the predetermined distance from the cellular phone 30 and the reception level of signal from the unit 10 received by the unit 20 is smaller than the predetermined value, or the unit 20 can not authenticate the identification code of the unit 10, the unit 20 stops transmission of the usage restriction cancellation signal to the PDA 40.

Abstract: A mobile communication terminal, which can be found promptly when lost, misplaced or stolen, is provided.

Abstract: Non-reception-controlled area information is stored in the non-reception-controlled area storage section of the reception control device for each mobile device ID. When the reception control device receives the disconnection signal and position information from the mobile device in accordance with the mobile device moving away from the key terminal, the presence/absence determination section determines whether or not the mobile device is within the aforementioned area. As a result of the determination, if the current position of the mobile device is within the aforementioned area, control for enabling reception for the mobile device is performed, and if the current position is outside the aforementioned area, control for disabling reception for the mobile device is performed.

Abstract: Non-reception-controlled area information is stored in the non-reception-controlled area storage section of the reception control device for each mobile device ID. When the reception control device receives the disconnection signal and position information from the mobile device in accordance with the mobile device moving away from the key terminal, the presence/absence determination section determines whether or not the mobile device is within the aforementioned area. As a result of the determination, if the current position of the mobile device is within the aforementioned area, control for enabling reception for the mobile device is performed, and if the current position is outside the aforementioned area, control for disabling reception for the mobile device is performed.

Abstract: A mobile communication terminal, which can be found promptly when lost, misplaced or stolen, is provided.