Design And Implementation Of VoIP System Based On Android

With the rapid development of smart phones,as well as the popularity of WIFI,3G and 4G networks,the demands for data business services are growing.However,the tariffs of traditional telephony are much more expensive than that of VoIP which is based on the data business.Therefore,it is important for actual market value to research and realize VoIP system based on smart phones.There are several weak points of the existing VoIP systems,such as not supporting multiple voice compression coding,weak on echo canceling,and so on.In this paper,we design and realize a VoIP system based on Android.The major work can be summarized as follows:(1)Based on the analysis of related key technologies in mobile IP phone system,we analyzed and designed the work flow for VoIP system based on Android.The major work includes analyzing and designing the overall work flow of VOIP business based on Android,and includes detailed analysis of system data flow.Specially,we focus on the data flow of the core business modules of VoIP system.(2)Based on the analysis and design above,firstly,according to the characteristics of VoIP,we uses the SIP protocol to meet the basic telephone work flow,and realize the state machine module based on SIP signaling which is used to handle basic phone business work flow.Secondly,we analyzed the audio codec technology and implemented G.71 1A and G.711? speech compression codec technology,SIP protocol automatic consultation and users voluntarily choose to common self-adaption decide the coding-decoding algorithm in a user call,which is strong in scalability.Implements the NAT firewall through technology at the same time to respond in case of there is a firewall in a network environment,system is able to communicate properly.Furthermore,research and realization of IP telephone echo cancellation algorithm,design and realization of the AEC algorithm based on signal tuned,can effectively solve the echo cancellation with fast convergence problem.(3)Finally,by consolidating the above key technologies,we implemented a VoIP prototype system based on the Android,and built experiment platform to test the performance of our system.Experimental results show that the system sound delay can well meet the demand of the echo cancellation algorithm delay,convergence of echo cancellation in part to superior to the traditional LMS Newton algorithm,meet telecommunications VoIP system design requirements.In the end of the paper,we show the applications of the developed Android-based VoIP prototype system.