ent: contains personalized information defining how sub- scribed services are provided and presented to the user. Service capabilities: bearers defined by parameters, and/or mechanisms needed to realize services. These are within networks and under network control. Service capability feature: functionality offered by service capabilities that are acces- sible via the standardized OSA interface. Service capability server: functional entity providing OSA interfaces to an application. Value-added service provider: provides services other than basic telecommunications service for which additional charges may be incurred. Virtual home environment (VHE): concept for personal service environment porta- bility across network boundaries and between terminals. 9.6 THE ARCHITECTURE OF SERVICE NETWORKS 9.6.1 GENERAL What is described here is the 3GPP/Parlay architecture. The OMA concept is similar as seen in Figure 9.4. The heart of the technical solution is a framework or platform with many supporting functions for service handling, security, QoS, SLA and other tasks. The basic architecture is called VHE/OSA. VHE/OSA supports three of the domains mentioned above: the network owner that could be called the home environment operator; cooperating roles such as content and application provider, VASP and HE-VASP (and other partnerships); and finally the core network access. VASP and HE-VASP are defined above. 9.6.2 IMPLEMENTATION OF VHE/OSA Open service architecture (OSA) is a concept defined by 3GPP and Parlay. It specifies services available to applications on application servers over standardized programmable Service Network Service network Applications Applications Applications Open APIs (e.g. OSA/Parlay API) Service enablers Resource managers etc Network protocols (e.g. MAP, CAP, INAP, H.323, SIP etc.) Call/Session control (PSTN/ISDN) IP Multimedia /UMTS (SIP/H.323) Incl. IN Access CAMEL independent H.248 solutions Connectivity network (IP and/or ATM) Wireless Wireline access access Figure 9.5 Open service architecture with