SPLAT: a unified SIP services platform for VoIP applications<FNR></FNR><FN>An early version of the paper appeared in ICCCN 2004. </FN>.

The steady improvements in the networking infrastructure and ever increasing broadband penetration has fueled the resurgence of voice-over-IP (VoIP). One of the important contributors to this growth has also been the development and wide acceptance of the session initiation protocol (SIP). However, the current usage of SIP requires a per-application deployment (each application using its own SIP stack). In addition to shared port number problems, this leads to a narrow development of SIP based services, even though SIP, as a protocol, offers incredible opportunities for enabling various applications simultaneously. In this paper, we propose SPLAT—a unified SIP platform, consisting of a client-side SIP service and supporting network infrastructure blocks, that provide unified mechanisms to execute generic SIP functions through an exported higher level API. Applications can leverage the API and ready-made building blocks for creating richer interfaces without significant and often repeated development effort, e.g. a conferencing server coupled with a gaming server can provide context-aware audio conferencing between occupants of a particular game room. Importantly, the SPLAT framework is available to all applications including the ones not inherently based on SIP and thus presents a great opportunity for enhancing such applications. The SIP service API is designed to be extensible and provides novel higher level functional primitives like ad hoc conferencing and seamless transition of sessions. In addition, it also exports a low level interface for specialized applications that need direct access to SIP call flows. Another feature of the service is that it allows a user to plug-in an end device (softphone, IP phone, PSTN phone) of his/her choice on a per-session basis. We demonstrate the richness of the API by describing prototypes for enhancing various applications as well as new converged applications. Copyright © 2006 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]