Peer-to-Peer SIP Communication in Mobile Communities

This paper presents a realization of a multi-service P2P overlay architecture that allows for establishing SIP multimedia sessions between mobile community members with little or no need for centralized servers of any kind. The overlay architecture forms a cost efficient platform for providing innovative mobile services. As an example, this paper presents an implementation of a mobile P2PSIP VoIP service. The implementation allows a mobile phone user make voice calls using resources of the P2P overlay. The mobile phone user may freely use standard call manager and contact list in a mobile phone. The paper also presents a method for locating relay servers that are used in NAT traversal.