Patent ID: 7606910

Claim:
A method, comprising: receiving a service request from a network device of a user, wherein said service request is a session initiation protocol invite request; checking, in a network control device, whether the user is registered to a network or not, by referring to information about a registration status of the user stored in a home subscriber server or in the network control device being a proxy call state control function or a serving call state control function, wherein the network offers services to registered users; and when the user is not registered, generating a response message including warn information and sending the response message from the network control device to the network device of the user, wherein the response message is a session initiation protocol 403 forbidden message; wherein the warn information triggers an automatic registration in the network device of the user, in which the network device of the user sends a register request to the network control device automatically when the network device of the user receives the response message.