More and more people use voice over IP instead of traditional telephone networks. The Session Initiation Protocol (SIP), a protocol for session management in general, becomes the standard protocol in use. However, SIP relies on central servers and thus maintaining the infrastructure is costly. This results in the trend to transfer peer-to-peer concepts to SIP to overcome administration efforts due to self-organisation of the participants.In this paper, we propose a novel JXTA-based peer-to-peer architecture for SIP signalling. JXTA is a generic and open peer-to-peer platform, which provides basic infrastructure services for building peer-to-peer applications. Our concept does not need central entities for maintaining the SIP traffic, while maintaining compatibility with standard SIP. Additionally, we seamlessly added service location capabilities into our infrastructure to support service discovery in dynamic environments. We evaluated our concept in comparison to standard SIP within three scenarios: local area network, point-to-point network and wide area network. The results show that our approach fits well in terms of response time but results in more traffic for maintaining the peer-to-peer overlay.