et 1.2.4.3 Code Generation 1.2.5 Related Work Service Control Layer 1.3.1 Limitations in IMS Service Control 1.3.2 Service Control Layer Architecture Service Delivery Platforms 1.3.2.1 System Architecture 1.3.2.2 How Does It Work? 1.3.2.3 How Is It Configured? 1.3.3 Related Literature Illustrative Example 1.4.1 Call-a-Cab Scenario Discussion References 1.1 Introduction Convergence between the two largest networks (Telecom and IP) is taking place very rapidly and at different levels: (1) network level: unification of IP networks with traditional Telecom networks through evolving standards (Session Initiation Protocol (SIP), Realtime Transfer Protocol (RTP), SS7, 3G) to support interopera- bility; (2) service level: traditional Telecom services like voice calls are being provi- sioned on the IP backbone (VoIP), while traditional IP services (most data-driven services such as multimedia, browsing, chatting, gaming, etc.) are accessible over the Telecom network. Significant investment has been made at different layers of the converged stack, toward supporting data-driven enriched services such as multimedia, gaming, browsing, and SO on. Such investments range from core network infrastructure changes (2G to 2.5G, leading to 3G, 4G) to adoption experiments with several standards (e.g., Wireless Application Protocol (WAP)) to support data-driven ser- vices (e.g., news feeds, mobile commerce, location-based service access), tradition- ally accessed over the IP network. Most content providers today have a mobile version of their information portals, which is accessible using mobile and cellular devices. Different game changing and competing technologies (e.g., Global Positioning System (GPS) versus cellular triangulation-driven location services, VoIP versus traditional telephone calls) in this converged market place are driving the big players to force an evolution in their business models. With the market reaching saturation in several countries and revenues from voice calls decreasing rapidly, Telecom operators are agg