subscriber and enterprise domains in the SDP framework. The RST reference point is implemented across the GSOA containing service functions. The interfaces offered by this GSOA hide the complexity of physical network resources used within the end-user, service subscriber, connectivity provider, converged network, and OSS/BSS domains. The RCT and RTT reference points are implemented across the GSOA housing the resource functions and the physical resource layer. Both physical resources and their functions span across end-user, service subscriber, connectivity provider, converged network, and OSS/ BSS domains. Therefore, in the SDP framework, the service-related GSOAs house varying levels of service enablers with technology neutral interfaces that adequately implement NGN reference points. For completeness, we also evaluate the SDP framework against the general SDP architecture in Figure 2.2 to show the frame- work's benefits. This evaluation is shown in Table 2.1. 2.6 Implementing a Service Delivery Platform To realize the SDP framework, we implement all its GSOA layers across all domains, using standards-based technologies. These technologies include the IMS functional entities and the Parlay and Parlay X set of API standards. The resulting SDP archi- tecture is shown in Figure 2.6. 2.6.1 Mapping Technologies Using the full SDP framework as a foundation, we map the existing network resources to the physical resource layer. For instance, physical resources are imple- mented using the access network Gateway GPRS Support Node (GGSN), media gateway, signaling gateway, media stores, and billing systems. The IMS functional entities detailed in [18] are used for the lower resource and service function GSOAs. For the resource functions the Policy Decision Function (PDF), Media Gateway Controller Function (MGCF), Breakout Gateway Control Function (BGCF), and Media Resource Function Processor (MRFP) are used. In the OSS/BSS domain, the IMS provides the Charging Gateway Function (CGF). Service Delivery Platform for the Next-