igure 4.54. Understanding Changing Telecommunications - Building a Successful Telecom Business Access transport Access transport = Optical rings used when applicable Service layer Internet Other operator's server Large/Medium server enterprises network server SGSN, GGSN Control 'LAN' funciton Access Access IP packet backbone router 'PBX' transport Frame relay transport router Circuit mode, (MGW) router (MGW) Ethernet Access ATM, IP IP/VPN (MGW) transport (MGW) Access Access Access Access C transport transport, GSM/EDGE transport DSLAM transport Homes & SMEs WLAN hot spot Coper xDSL Resource sharing Fibre Ethernet DSL WCDMA Figure 8.12 The horizontal network seen from the access side, with the demanded services at the top The figure represents a fairly unified backbone, control layer (two main parts) and service layer. Many people suppose that we are heading towards a final, hopefully simple network with SIP and IP as the main technologies for signalling and the network layer. The service layer provides application supporting VAS services (e.g. SAT/USAT, Java, positioning, messaging and WAP), network FP supporting IN services such as CAMEL, and 'middleware features' such as XML, and MPEG-4 and other coding/compression standards opting for economy of service. 8.4 DEVELOPMENT TRACKS Let us use Figure 8.12 as a base to identify some roles and tracks, and also for references to other chapters of the book. It is obvious that it is the access network that represents the main differentiation between actors. For more information on the access area see Chapter 13. The backbone is found in Chapter 12, the control network with SIP signalling in Chapter 14 and the service network in Chapter 9. The edge nodes are treated in Chapter 11. Case 1 in Figure 8.12 is an enterprise data access, which could be operated by the incumbent operator, other competing fixed network operators or operators targeting enter- prise traffic, often operating globally. The technical solutions for wide area corporate networks develop from leased lines