control which does not lend itself well to rapidly changing business and market requirements-especially in the case of mashup-based ecosystems. Further, current approaches tightly couple Telecom services with back-end IT applications such as Customer Relationship Management (CRM) and billing, by means of hard coding of service management policies and business logic into the application logic itself. In a mashup-driven ecosystem, this introduces downsides in third-party service deliv- ery models for both the operator and the third party. From the operator's perspec- tive, it might have to entrust service control-such as charging-to third parties for off-network services which may not always be desirable. From the third-party's perspective, it may have to adapt service logic to an operator's environment, which introduces complexity when seeking to partner with more than one operator. This is further illustrated in Figure 1.5, which shows that today's service logic is tightly integrated with subsystems such as billing (1), adding complexity and redun- dancy to service logic. Further, some of the subsystems are tightly integrated with other subsystems (2) leading to ad hoc and inefficient management of these services. In either case, this often leads to a static and costly one-size-fits-all model. It is difficult, for example, to quickly change the way that services behave in response to an ever-changing business environment, for example, introduce variable charg- ing schemes per user/user group, change business policies such as Service-Level Agreements (SLAs)-without resorting to costly and time-consuming code Billing Content services Service Figure 1.5 Traditional IMS service delivery. Service Delivery Platforms changes. In a Web 2.0-oriented ecosystem, it not only becomes a nightmare for operators to effectively partner with third-party services, but also makes it infeasi- ble to manage self-owned applications. To address this shortcoming, we propose IMS-based service control architec- ture for offering next-gener