ion of API is application interface Many of the APIs correspond to service capability servers (SCSs). SCSs are service enablers that provide the applications with service capability features, and are abstractions from underlying network functionality. From the viewpoint of applications, an SCS can be seen as a resource gateway to the core network. Examples of service capability features offered by the SCSs are call control and user location. A common standard that provides a model of the network capabilities is called Parlay. See Figure 3.35. The 3GPP is committed to open interfaces for SIM cards with defined APIs making it possible for application developers and network operators to develop services. In an optimal situation the programmer has API access to all independent parts. See for example Figure 3.36. The applications should thus be separated from the core network, leading to 'ser- vice convergence' at application level. SCS/service enablers with a resource management Parlay The basic idea Parlay API Telecom network Parlay API Figure 3.35 Parlay: provides a model of the network capabilities Networks and Technologies User data Business relation Business relation User segments FAB = User Content Life-stage dimension interface, with Value/attitude dimension providers fulfilment, assurance and Services, QoS, Security billing perception Roles Business relation SM = Service management Applications Profitability calculations NM = Network (Applications/Service) management enablers - Middleware FP elaboration Control Fundamental technical plans Core connectivity Investments Access Access Figure 3.36 Possible API interfaces in the future network function cater for the access to various network resources. See also the Chapter 9. The application level then becomes the 'melting pot' for all types of IP services/service com- binations, also providing an 'end-user personalized service environment' independent of access type. 3.11.2 MIDDLEWARE Another important part of the solution is the re-use of middleware for differen