Research And Development Of Real-time Voice Communication System Based On SIP

With the development of mobile internet technology, using of the cellphone network terminal for the voice communication is becoming the trend of future development. SIP is the core of the next generation network media communication protocols, so for the research and development of the real-time voice communication system based on SIP is of practical significance and potential commercial value.On the basis of in-depth study of the SIP, the real-time voice communication system is developed by using the client/server model. The system’s overall communication architecture, system protocol stack and system software module are designed. The system client completes the development of application management module, the media processing module, user agent module and the SIP protocol stack. The server in the system, the use of Opensips installation and deployment server, realizes the functionality of the SIP registration server, proxy server and redirection server.The problems the voice communication system application Based on the SIP exists conduct research and propose the optimization scheme. ZRTP encryption scheme is used for solving the existent problem in SIP encryption, through using SAS values and HMAC sequence on the end of the media stream to ensure call safety. There is no third party attacks, this solution does not involve the use of the existing public key infrastructure PKI deployment and management issues. Design of multi voice codec project solves the SIP terminal voice communication compatibility issues. The multi voice codec priority function is realized, by setting this feature to giving priority to using user terminal platform custom codec for voice communication. Using the latest technology of WebRTC makes the filter and the current popular NLMS algorithm combining on the mobile terminal platform to eliminate acoustic echo. Design NLP nonlinear filter directly optimizes to the adaptive filter coefficients to achieve the goal of eliminating residual acoustic echo.Finally, on the mobile terminal platform the functionality and optimize performance to the system testing, the test results shows the development of system satisfys expectant reqirements.