Abstract: A service provider having various application servers gains access first to a relay server when a client which has been registered in the relay server intends to use a service provided by the service provider. Then, the relay server certifies the client and connects the client to the service provider. The relay server also performs an accounting operation incidental to services used by the client. For this purpose, a member/accounting management server is connected to the relay server and a database required for this purpose is provided by the member/accounting management service.