Recommendation ITU-T X.1123 describes the differentiated security service for secure mobile communication. The investigation of differentiated security service is important for both service providers and users. The service providers can use the differentiated security service to overcome the rigorous circumstances of wireless access networks and satisfy various users and services with different levels of security. The differentiated security service is realized by security policy with three layers. One layer is super security policy used as a value-added service that safeguards mobile communication with sensitive information. The second layer is baseline security policy used as the prevalent service that satisfies mobile communication without sensitive information. The last layer is no security policy, defined as the policy under which no security function is configured during communication.