Peer-to-Peer Session Initiation Protocol (P2PSIP) is a new technology being standardized in the Internet engineering task force. A P2PSIP network consists of a collection of nodes organized in a peer-to-peer fashion for the purpose of enabling real-time communication using the Session Initiation Protocol (SIP). In this paper, we present experimental results obtained by running a P2PSIP prototype in PlanetLab. Our prototype uses the Chord Distributed Hash Table (DHT) to organize the P2PSIP overlay and Peer-to-Peer Protocol (P2PP) as the protocol spoken between the peers. In the experiments, the performance of the system is studied under different churn rates and using different DHT maintenance intervals.