usage of CS paths through the Mobile Switching Centre (MSC). Non real-time services, e.g. Internet type (email, ftp, information ser- vices, etc.), will also continue passing through the GPRS network. While IP services may appeal to both, public and private, the latter may exploit more IP services such as IP telephony, person-to-person multimedia conferencing, mobile Inter- net, etc; CS voice telephony may initially remain the best solution for the mass market. On the other hand, if end-to-end mobile IP telephony consolidates its flexibility with minimized cost and high quality and IP native terminals are widespread, the mass mar- ket may embrace IP services very rapidly. Evolving NEs New NE lu-PS Internet & corporate IP lu-CS 3G MSC PSTN/ISDN Figure 3.4b 2G Elements evolving for UMTS R99. Figure 3.4b illustrates the evolving CN elements to meet the R99 specificationss. Notice that the evolution affects primarily the SGSN, MSC, and HLR. These elements will either have new architecture platforms or follow SW upgrade with selected HW addi- tions. The process will vary from supplier to supplier. The new element, i.e. RNC, cor- responds to the radio network. For completeness we next review the main functions and transition steps of the CS and PS network elements. The Value Added Services (VAS) platforms (e.g. voice mail, SMSC, IN, pre-paid, etc.), which also reside in the CN, will evolve at their own pace. 3.2.4 Circuit Switched (CS) Network Elements (NE) 3.2.4.1 The 3G Mobile Switching Centre (3GMSC) The 3G MSC will become the main element of the R99 CS network just as it is in GSM. In general depending on the manufacturers, a 3G MSC will include a VLR and a SSP to serve both GSM BSS and 3G RAN concurrently by incorporating both A and Iu inter- The UMTS Development Platform faces. The Iu interface will be realized through a HW upgrade, e.g. a plug-in board to the MSC in some cases, or an ATM module using a new HW platform connecting to the MSC in other cases. Thus, the same 3GMSC will control services and charging f