With constant stories appearing about computer hackers and other network breaches, security must be a top concern for any network operator as well as the end user. The migration to an Internet Protocol (IP)-based technology will expose the mobile operator and their users to security attacks similar to those attacks today associated with the wired Internet Service Provider (ISP). Third Generation Partnership Project (3GPP™) has defined two areas in which they address the security issue. In 3GPP TS 33.203, they lay down the security requirements between the IMS network and the end user (access security), and in 3GPP TS 33.210, they specify the security requirements in the core network domain (network security). Here, the core network domain would cover security between different IP Multimedia Subsystem (IMS) networks and also within a single IMS network.