he network for both enterprise and consumer markets by utilizing network features and capabilities, while it asked to enable the worldwide software develop- ment community to exploit the features of current and future networks and to bring the IT developer community into the Telecoms space. The Parlay framework was intended to make it easier for network operators and service providers to deploy many new applications and services, and to enable new business models for service providers. During the course of time, the standards bodies 3GPP, Parlay Group, and finally also ETSI joint forces to develop consistent API specifications jointly. After completion of the NGN Release 8 in 3GPP, the responsibility for the evolu- tion of Parlay specification had been transferred to the Open Mobile Alliance (OMA). Parlay/OSA is up to now the open standard for bringing Telecoms and IT together into one value chain. Parlay-X Telecom Web Services is the application interface that is published to developers and partners outside the Telecom network. The Parlay-X Web Services interface is attractive to many application developers, because of the strong support for Web Services in IDEs. The Parlay APIs are understood as A mediator API between Telecom networks and third-party applications A secure interface between Network Operators and ASs Open standards (specified by the Parlay Group and 3GPP, OSA) They raise the programming abstraction level and allow multinetwork applica- tions. The OSA/Parlay APIs are made up by defining: Framework interface set: Common functions required to enable services to work together in a coherent fashion, for example, authentication, discovery, manageability. Service Delivery Platforms Resource interfaces: Interfaces used between a Parlay Gateway and network ele- ments (not specified in Parlay). Service interface set(s): Common functions that deliver whole complex ser- vices or subcomponents of services, for example, Call Control, User Interaction, Content-based Charging, Location, Presence and Availability