oncept 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 API interfaces interfaces (application programming interface, API) See Figure 9.5 and Chapter 3. The services provided by the service network respond to the needs of the actor: New marketing and sales channels. Efficient tools and development environments. Another related important concept is virtual home environment (VHE), offering ser- vice roaming. The VHE is defined as a concept for personalized service portability across network boundaries and between terminals. The idea with VHE is that subscribers are consistently presented with the same personalized features, user interface and services, regardless of their access network or terminal (within