Applied Research Of The SIP Protocol In Multimedia Communications

With the rapid development of network technology and the popularity of network applications, it has also led to the development of a variety of IP-based applications. The Internet-based multimedia communications is one of the most important applications.At present, the more mature protocols of network multimedia communication are H.323 and SIP (Session Initiation Protocol), which respectively proposed by ITU-T and the IETF. SIP is the core protocol of the next generation of IP multimedia communications, which is a plain text-based signaling protocol, and it also can manage different intervention on the network sessions. Its main purpose is to address the communication problems of signaling control in the IP network and Softswitch. With simple, easy to expand, good compatible with other Internet protocol, SIP is suitable for Internet access and many other advantages, at the same time, it has gradually becoming an important agreement of the Next Generation Network and the 3G mobile multimedia applications.The article first analyzes research status of the SIP protocol at home and abroad, and proposes the contents of this article. Then introduces the basic concepts of the SIP protocol, SIP messages and transactions, the characteristics of the SIP and the call flow of SIP, and also compare with the H.323 protocol. Combining with the RTP, RTCP transport protocol, use SIP as a multimedia communication application layer control protocol, design and implement a SIP multimedia communication system based on Windows platform, made a detailed study on the design of the system's several modules and the main use of key technologies such as the video capture technology VFW. Give a detailed description including the oSIP protocol stack and RTP implementation. And choose the SIP Server 2008 as a test server for the multimedia system; test the functions of the system. At the end of the paper, make a summary and give a prospect.