gement and 'pre-paid' services are the result of the IN service. GSM and GPRS (General Packet Radio Services): As the requirement for sending data on the air-interface increased, new elements such as SGSN (Serving GPRS) and GGSN (Gateway GPRS) were added to the existing GSM system. These elements made it possible to send packet data on the air-interface. This part of the network handling the packet data is also called the 'packet core network'. In addition to the SGSN and GGSN, it also contains the IP routers, firewall servers and DNS (domain name servers). This enables wireless access to the Internet and the bit rate reaching to 150 kbps in optimum conditions. GSM and EDGE (Enhanced Data rates in GSM Environment): With both voice and data traffic moving on the system, the need was felt to increase the data rate. This was done by using more sophisticated coding methods over the Internet and thus increasing the data rate up to 384 kbps. OVERVIEW OF MOBILE NETWORKS 1.2.3 Third-generation Networks (WCDMA in UMTS) In EDGE, high-volume movement of data was possible, but still the packet transfer on the air-interface behaves like a circuit switch call. Thus part of this packet connection efficiency is lost in the circuit switch environment. Moreover, the standards for developing the networks were different for different parts of the world. Hence, it was decided to have a network that provides services independent of the technology platform and whose network design standards are same globally. Thus, 3G was born. In Europe it was called UMTS (Universal Terrestrial Mobile System), which is ETSI-driven. IMT-2000 is the ITU-T name for the third-generation system, while cdma2000 is the name of the American 3G variant. WCDMA is the air-interface technology for the UMTS. The main components include BS (base station) or node B, RNC (radio network controller) apart from WMSC (wideband CDMA mobile switching centre) and SGSN/GGSN. This platform offers many Internet- based services, along with video phoning, imaging, etc. 1.2.4 Fou