Abstract: As to satisfy users' different demand with the telecommunication, access networks' heterogeneity has been the inevitable trend of next generation networks. To solve the bad continuity of the telecommunication caused by not only the unstable performance of the heterogeneous network and terminals but also the real-time change of users' demand,we proposed a user-oriented and RI’P/RhCP based implementation of intelligent handoff technique of VoIP. By means of the extension and application of RTP/RTC;P protocol, we can detect the real-time end-to-end network QoS performance in VoIP service, and collect the information of users and the performance of terminals and networks, so the system could utilize the performance thresholds of the service, the network environment, the performance of terminals and users' preferences to intelligently handoff users to the best network and terminal,meeting the demand of the service contmmty and access diversity.

Key words: Heterogeneous nctowrk, VoIP, QoS, RTP/RTCP, Intelligent handoff