Abstract

Since the telephone was invented, it has revolutionalized the telecommunications and enabled people to talk to each other over long distances. Through the years, the telephone has been greatly improved and many new models have been developed to serve the different needs of the diversified set of users. Peer-to-peer systems inherently have high scalability, robustness and fault tolerance because there is no centralized server and the network self-organizes itself. These features can be used in order to construct peer-to-peer internet telephony systems where there is no central server and with a lower cost than the current internet telephony systems. In this thesis, we propose a fully distributed peer-to-peer architecture, called SIP2P, for the Session Initiation Protocol (SIP). Peers connect directly to other peers, constructing an overlay network of peers which communicate to each other in order to provide the same services as the central server in the conventional SIP. The nodes that define the overlay not only act as an ordinary SIP user agent but they can also perform all together the role of the SIP proxy, SIP register and the SIP location service. The behavior of the conventional SIP servers is distributed over all the nodes participating in the overlay. An implementation of the SIP2P system concludes the thesis in order to validate and evaluate its distributed design