Solutions to security issues with legacy integration of GSM into UMTS

Mobile networks are constantly changing and adapting to the needs of users and providers. The legacy global system for mobile communications (GSM) step in the evolution of mobile networks has by far the largest installed user-base. The very large user-base has made it a requirement for providers to modify their future systems to interoperate with the legacy GSM system. The security problems brought about by this legacy integration have a major impact on the security improvements developed for the universal mobile telecommunications systems (UMTS). This paper proposes simple and effective solutions to reduce the possible attacks on the UMTS systems due to the above integration. First we propose a subtle modification to the GSM security protocols as a standalone solution, and then a modification to the UMTS security protocols is proposed as a second solution.