The security deployment of early IMS

3GPP IP multimedia subsystem (IMS) provides IP-based session control capabilities based on the SIP protocol. Although full support to 3GPP TS 33.203 security features is preferred from a security perspective, it is acknowledged that early IMS implementations exists which do not support these features. 3GPP TR 33.978 define some security mechanisms to protect early IMS, but there are still some security issues, e.g. the signaling security, roaming security, NAT and interworking, which need to be resolved in the deployment of early IMS. This paper presents a new deployment of early IMS which focus on the security from the access network to the core network