The Design And Realization Of VoIP GateWay Based On SIP

In recent years,with the rapid development of computer networks,real-time multimedia applications based on IP packet switch networks are more and more,among them,VoIP technique has provided a strong and valid means for long-distance telecommunication with its low expenses and abundant of business platform. VoIP has become a hotspot of technology research nowadays.The key technology in the development of VoIP is signaling technology. Rright now the most widely used protocols are H.323 and SIP .But the protocol architecture of SIP is very simple and easy to realize,and SIP is convenient to expand. All these advantages show that SIP is more fit for the future development of networks.In the thesis,the design and realization of VoIP gateway based on SIP are introduced. At first,the basic theories of VoIP are introduced,including the communication theory, VoIP system element, key technology of VoIPand VoIP gateway are focused on. Then an important protocol for multimedia communication system--SIP is introduced, including the development, main function, application structure and message structure. And at last the author compares SIP with H.323 standard.Through the deeply analysis of SIP, the author provides a solution of VoIP gateway, including the hardware module block diagram, software module solution and realization. In addition, software module solution and realization of the gateway is the point in this article. This charpter, according to the software architecture, discribs the realization of three important module—CGI,voice process module and SIP stack module. Then the realization of voice process and SIP stack are discussed in detail. In the end, the thesis makes expectations of VoIP.