I), it also has impact in the service configuration options and the access Evolving Mobile Networks to the Core Network (CN). Hence, the 3G, or more specifically UMTS requirements in this section cover three main areas, i.e. services, air-interface, and core network access. 1.2.1 UMTS Services Aspects The scope of services can be largely focused on different issues like service manage- ment, charging and billing, terminals, network management, quality of service, and se- curity. Here, however, we will be looking at services from the principle side in other to establish a framework to present the UMTS air-interface. An extract of the service prin- ciples outlined in the ETSI specifications UMTS Services aspects - Service Principles and UMTS Services [4] and Services capabilities [16], can be summarized as follows: UMTS is the realization of a new generation of mobile communications technology for a world in which personal communications services should allow person-to-person calling, independent of location, the terminal used, the means of transmission (wired or wireless) and the choice of technology. UMTS shall therefore be in compliance with the following objectives: (a) to provide a single integrated system in which the user can access services in an easy to use and uniform way in all environments; (b) to allow differentiation between service offerings of various serving networks and home environments; (c) to provide a wide range of telecommunications services including those provided by fixed networks and requiring user bit rates of up to 2 Mbits/s as well as services spe- cial to mobile communications. These services should be supported in residential, public and office environments and in areas of diverse population densities. These services are provided with a quality comparable with that provided by fixed net- works such as ISDN; (d) to provide services via hand held, portable, vehicular mounted, movable and fixed terminals (including those which normally operate connected to fixed networks), in all enviro