IMS service development API and testbed

The IP multimedia subsystem defined by the Third Generation Partnership Project is the architecture merging the Internet and telecom worlds. The IMS was designed to make it easy for third-party developers to make their applications available to all IMS users, and by doing so provide more than only the basic telecom services like voice, messaging, presence and contact management. However, good knowledge of the IMS network architecture and the underlying Internet protocols is still needed to develop IMS applications. In addition, telecom expertise is needed to deploy the application and provision users. To ease the development and deployment process, it is essential to provide application developers with APIs and similar tools available for Web 2.0 application development today. In this article we explore the architectural and protocol aspects that enable third-party IMS application development and deployment. We also study how the applications will coexist with other applications already deployed in the IMS. Moreover, we describe Java libraries exploiting the functionality of the IMS both in the terminal client and within the core network. We also show how these Java libraries can be used for developing and deploying new applications in an IMS testbed, which provides IMS functionality over commercial 3G networks.