SIP (session initiation protocol) has been chosen as the protocol for IP-based multimedia call control for 3G wireless networks. P2P (peer-to-peer) networks are useful in a wide range of application scenarios in personal, commercial, public and military environments. In this paper a JXTA-based SIP communication system for P2P wireless networks is proposed, which is compatible with other JXTA systems as well as SIP systems. The architecture is based on P2P-SIP. It takes advantages of both JXTA protocols and SIP. A JXTA-SIP bridging module is presented, which makes the interoperation between the JXTA overlay and the SIP overlay possible. A prototype is implemented and validated.