Publisher Summary Most consumers are naive about the security of their wireless phone calls. The level of security required by an individual consumer will most likely be much less than that required by a unbounded mobile communications (UMC) enterprise solution, but all must have some level of security. The security motivations of a consumer and an enterprise solution will be different. In today's cellular world, security is embedded within the system, and the user is not required to take any action when attaching to the mobile network. Authentication is performed not based on the user but rather on the device. Once past the device authentication phase, a security key exchange protocol sequence is completed, and all signaling and audio traffic from the mobile handset through the mobile network is automatically encrypted. In such a state, any person may use this phone, but all information transmitted or received will be secure.