Teletraffic theory is applied probability theory suitable for the performance evaluation and dimensioning of communications networks, and Teletraffic Models have been an inseparable part of the development of telecommunications and ICT infrastructure from the very beginning of their existence. Over recent years, Teletraffic problems have changed substantially as a result of the changes in the telecommunications area towards integration of the services, Internet and mobile communications, as well as networks convergence. Each and every newly introduced type of a network technology is followed by a substantial increase in both the number and the complexity of problems that need to be resolved. No matter what these developing changes may bring, the essential task for Teletraffic remains the same edash; to determine and evaluate the relationship between the QoS parameters, the parameters that determine the intensity of connection requests (calls) and the demanded resources, and the parameters that describe available network resources (capacity). These relationships provide a basis for developing Teletraffic models used for designing, performance analysis and optimization of systems and networks.  This book presents a comprehensive guide to almost all network technologies or to network services.