With the evolution of mobile phone technology and the emergence of new services, which for the most part bring personal information or restricted data of users, mobile phone systems also brought innovations in regards to information security. Within this scenario, there are many studies focused on the analysis of security in third generation (3G) mobile phone networks, but mostly engaged in analysis of specific protocols for individual projects. This book intends to study in the integrated form the several protocols such as authentication, confidentiality and data integrity. From this study, it seems like the impact of these security mechanisms, despite robust, cause little loss of performance across the 3G system, specifically the Universal Mobile Telecommunication System (UMTS). With simple and comprehensive information on the structure, function and mechanisms of network security, this book can be an enriching experience for students, professionals and enthusiasts in engineering and technology areas that are looking for new knowledge and telecommunications research.