Patent ID: 8045540

Claim:
A method, comprising: determining whether transport layer security is supported in a hop to a next session initiation protocol proxy; when the transport layer security is supported, establishing a transport layer security connection from a first session initiation protocol proxy to the hop of the next session initiation protocol proxy, wherein the first session initiation protocol proxy is at an internet protocol multimedia core network system, and the next session initiation protocol proxy is at a network comprising a non-internet protocol multimedia core network system; requesting a certificate from the next session initiation protocol proxy; receiving the certificate; verifying, during the establishment of the transport layer security connection, the certificate and a trustworthiness of the network of the next session initiation protocol proxy, wherein the determining determines that the transport layer security is supported to the next session initiation protocol proxy, when establishing the transport layer security connection; retaining privacy information in one or more session initiation protocol messages, when the certificate and the trustworthiness of the network is verified; when at least one of the transport layer security is not supported, the certificate is not verified, and the trustworthiness of the network is not verified, removing the privacy information from the one or more session initiation protocol messages; and forwarding the one or more session initiation protocol messages.