Network authentication system and method for IP multimedia subsystem

The invention discloses an IMS right-identification network system by adding a interface supported right-identification signaling on IMS network, which comprises: a MS for right-identification calculation, a HLR, and said IMS network to transfer parameter and compare calculation result. It also provides the method: after receiving the register request from MS, IMS acquires calculation result of parameter from HLR to save the result and send parameter to MS; MS calculates and sends right-identification result to IMS network; IMS decides whether the results accords from MS and HLR. This invention is simple and has well reliability.