SOSIMPLE: A Serverless, Standards-based, P2P SIP Communication System

Voice over IP (VoIP) and instant messaging (IM) systems to date have either followed a client-server model or have required the use of clients that do not follow any VoIP or IM standard. We present SOSIMPLE - a fully decentralized, P2P, standards-based approach to communications. By building on the existing SIP/SIMPLE infrastructure for VoIP and IM, we support reuse of clients, network infrastructure, and open-source protocol stacks designed using current standards. By avoiding traditional centralized architectures, SOSIMPLE addresses corporate privacy concerns, eliminates dependency on constant Internet connectivity, and supports ad hoc groups. SOSIMPLE implements a DHT overlay based on Chord (Stoicha et al., 2001) using SIP messages, replicating location information for reliability. The DHT is used only for lookups, with actual communication passing directly between clients. We discuss important issues for security and authentication, as well as adaptations of conventional P2P routing for the social networks typical of personal communications. We are testing a prototype implementation of SOSIMPLE and anticipate a public release in the near future