ring plan for the example network MSISDN number range E.164 254 733 0000&&9 GT (global title) number range 254 733 0010&&9 MSRN numbers 254 733 0020&&9 HO numbers 254 733 1&&9 Subscriber MSISDN numbers E.212 639 02 1&&9 IMSI number range The E.164 number format is CC + NDC + SN where CC = country code NDC = national destination code SN = subscriber number The E.212 number format is given as MCC + MNC + MSIN where MCC = mobile country code MNC = mobile network code MSIN = mobile subscriber international number The engineering numbers consist of network element global titles, MSRN numbers and HO numbers. The subscriber numbers consist of number ranges for test users, operator employees and commercial users. Table 4.7 presents a number allocation for the example network. 4.3 Network Evolution 4.3.1 GSM Network A 2G or GSM network consists of a base station subsystem (BSS) and a network subsystem (NSS) (Figure 4.6). The GSM network is suited to provide voice telephony services for mobile subscribers. In 2G phase 2+, the GSM network has been further enhanced with a general packet radio service (GPRS) to provide high speed data services for GSM subscribers. The GPRS uses a packet mode technique in GSM to transfer high speed and low speed data and signalling in an efficient manner. The GPRS optimises the use of network and radio resources. Core Network Planning and Optimisation Internet (TCP/IP) 2G SGSN mobile Base Station Subsystem Network Subsystem GSM BTS mobile PLMN/PSTN/ISDN mobile Indoor 2G IN SCP Figure 4.6 GSM network architecture (SRR, service routing register) 2G GPRS Network The GPRS system brings the packet switched bearer services to the existing GSM system. Support for GPRS in the HLR includes GPRS subscriber data storage, a standard MAP interface to the serv- ing GPRS support node (SGSN) and a subscriber data management interface for GPRS subscriber data. 4.3.2 3GPP Release 99 Network Release 99 Network Architecture The architecture of this network is shown in Figure 4.7. 3G MSC in Release 99 Architecture