Patent ID: 7673328

Claim:
A network system comprising: individual service provider devices ( 14 A, 14 B, 14 C) each having a first authentication server ( 22 ) and access point terminals ( 20 A, 20 B, 20 C) to which user terminals ( 50 , 52 ) of users who contract a corresponding one of the individual service provider devices are connected, the access point terminals connecting the user terminal to a network; a parallel service provider device ( 16 ) connected to the network and the individual service provider devices ( 14 A, 14 B, 14 C), the parallel service provider device having a roaming contract with the individual service provider devices and including a second authentication server ( 32 ) and no access point terminal; wherein each of the individual service provider devices ( 14 A, 14 B, 14 C) comprises: determining means for determining (S 6 ) whether a user who issues a connection request from a user terminal connected to one of the access point terminals is a contracted member of the parallel service provider device; transmitting means for transmitting (S 14 ) the connection request to the parallel service provider device ( 16 ) to cause the second authentication server ( 32 ) of the parallel services provider device ( 16 ) to perform user authentication when the user is the contracted member; authentication means for causing the first authentication server ( 22 ) of the individual service provider devices ( 14 A, 14 B, 14 C) to perform user authentication (S 8 ) when the user is not the contracted member; connecting means for connecting the user terminal connected to one of the access point terminals to the network and charging the user for connection when a result of user authentication is good (S 10 , S 18 ), said parallel service provider device comprising: receiving means for receiving a user name for a user terminal of a user who requests a signup; and further determining means for determining whether e-mail addresses including a combination of the input user name and sub-domains of the parallel service provider device has been registered so as to register one of non-registered e-mail addresses.