Patent ID: 7418727

Claim:
A security authentication method for a PC client, comprising: sending by the PC client a registry request to a user server with a user ID and a password; performing, by the user server, a first authentication based on the user ID and the password, if the first authentication being successful, creating a field used for re-authentication and returning the field to the PC client through an authentication successful message; when initiating a call each time, transmitting, by the PC client, the user ID and the field returned by the user server as well as a calling number and a called number to a service server; transferring, by the service server, a request for re-authentication including the user ID and the field as well as the calling number and the called number to the user server each time the service server receives a call from the PC client; performing, by the user server, a second authentication based on the user ID and the field each time the user server receives the request for re-authentication, and if the second authentication fails, rejecting the call, otherwise accepting the call and returning information of a called subscriber to the service server; and accepting, by the service server after the second authentication, the call and establishing the call.