SERVICE SYSTEM AND SERVICE SYSTEM CONTROL METHOD

PROBLEM TO BE SOLVED: To attain site access control of high trustworthiness, in a service provider device. SOLUTION: A network provider device associates user information on a user of a user device with line information on a line connected with the user device and stores them. When the network provider device has received a user authentication request for user authentication for the user device by redirect communication through the user device from the service provider terminal, it transmits, to the service provider device by redirect communication through the user device, a user authentication result obtained by performing user authentication using the user information associated with the line information on the line connected with the user device. The service provider device, when it has received the user authentication result for the user device by the redirect communication through the user device from the network provider device, controls site access using the user authentication result. COPYRIGHT: (C)2008,JPO&INPIT