Patent ID: 7206850

Claim:
A communication system including a terminal, a relay device, and a service provider, wherein: (a) said terminal sends a user name to said relay device; (b) said relay device receives the user name from said terminal, generates an authentication character string randomly, and sends the authentication character string to said terminal; (c) said terminal receives the authentication character string, shows the authentication character string to the user in association with the user name, allows the user to convert the authentication character string into a password-character string, and sends a password-character string input by the user to said relay device; (d) said relay device receives the password-character string from said terminal, and assigns said terminal a communication identifier in association with the user name in a case where the password-character string is equal to a character string converted from the authentication character string based on a rule in association with the user name; (e) said terminal sends a service-request message, whose addresser corresponds to the assigned communication identifier and addressee corresponds to a communication identifier of said service provider, to said relay device; (f) said relay device receives the service-request message from said terminal, and sends the service-request message to said service provider; (g) said service provider receives the service-request message from said relay device, and sends an inquiry message for inquiring whether to provide a service to the communication identifier specified in the service-request message, to said relay device; (h) said relay device receives the inquiry message, and sends a response message, to said service provider, specifying to provide a service, in a case where the communication identifier specified in the inquiry message has been assigned in association with the user name, and, if not, specifying not to provide a service; (i) said service provider receives the response message from said relay device, and sends a service-providing message, whose addressee corresponds to the communication identifier specified in the service-request message in a case where the response message specifies to provide a service and whose addresser is said service provider, to said relay device; (j) said relay device receives the service-providing message from said service provider, and sends this to said terminal; and (k) said terminal receives the service-providing message from said relay device.