om British Telecom allows developers to integrate core Telecom functionality with other Web services into a single application, while allowing application-specific logic to bind the component services. Similar to our work, Web21C hides the complexity of Parlay-X or SIP by exposing these Telecom func- tions as higher-level APIs. Similarly, Connected Services Framework Sandbox [18] from Microsoft provides high-level Web service interfaces via its SDP that hide low-level Telecom protocol-specific constraints and allow the creation of Managed network mashups. However, both of these can benefit by incorporating a struc- tured and rich format such as the T-Rec proxy model. 1.3 Service Control Layer The ease and flexibility of service creation and orchestration (composition) offered by the SDPs have resulted in a plethora of advanced value-added services developed and deployed in Telecom networks. The management of these services is a very complex but very critical operation for the success of any service provider. The key management functionality in converged networks is IP-based service control that ensures many different services running over a single universal IP network, while controlling the customer access by dynamically configuring and provisioning them in the runtime. Thus, service control requires knowledge of what occurs in the network and the ability to effectively manage it in a flexible and customizable way. Considering the fast-changing Telecom services and application space, some desir- able service control features are 1. Swift adoption to market changes and customer preferences. 2. Support of many different types of business models (e.g., changing the charg- ing model of a service for a category of users). 3. Effective participation in a value network. Today's approach to IP-based service control is typically inflexible and costly to maintain. That is, service control requirements are hard-coded into service logic (IN, SIP Servlet, etc.) during service development with limited configuration options. Wh