be classified as advanced fundamental plans, for example advanced routing (IN-VPN, virtual private network), advanced numbering (number portability, universal number) and advanced charging (prepaid, televoting, freephone) In CAMEL (customized applications for mobile network enhanced logic) there are functions for changed B-number and changed tariff. Figure 8.7 (also Figure 3.39) shows alternative IN implementations. In Figure 8.8 a number of 'VAS' (value-added services) services are indicated. In principle these services are included in the range of service enablers in this book. CAMEL was covered in Book 2. Figure 8.6 is somewhat complicated and does not represent the initial and target stages. Therefore a series of figures are included to show the gradual development. This also represents what is called a development track in the book. See Figures 8.8-8.10. Figure 8.8 is a bridge to GSM and similar systems of the second generation, with UTRAN, SGSN and GGSN as main additions. Figure 8.8 shows release 4 with a separation between control and connectivity layer for CS domain multimedia and the evolving service layer. Figure 8.10, finally shows a simple target network version, based on IP. Let us then turn to an 'all-access' network. It could be represented by the conceptual Figure 8.11, taking care of the requirement for a competitive solution. Observe that this figure makes no differentiation in the access layer, which is shown in Figure 8.12. Service Implementation Alternative Legacy mobile Multimedia Applications & access signalling network IP networks sevices *) network R-SGW *) CAP = CAMEL application part IP-SIP CAMEL = customized application HSS *) Multimedia for mobile network enhanced logic Control Domain PS Domain T-SGW *) UTRAN PSTN/ Legacy/External GERAN MSC server GMSC server T-SGW *) Transport signaling gateway CS Domain Applications & services *) HSS *) R-SGW *) Multimedia by H.324M Roaming SGW Signalling interface these elements are duplicated for figure Signalling and data transfer interface layou