Research On NAT-Traverse Technology And A Implementation Of SIP-Based Multimedia Communication System

Due to its tremendous advantage, multi-media communication system is becoming one of the rapidly developing application technologies.But lots of multi-media communication systems are difficult to adapt to the existing network environment, especially in the problem of NAT-Traverse, which leads to they can't communicate.With the competition of the telecom market getting fiercer, the Next Generation Network becomes the hot topic of research. As the next generation telecom switch equipment, the Softswitch is based on the VoIP technique, which makes the PSTN and Internet united to TCP/IP. The telecommunication based on Internet, represented by VoIP, is facing a good opportunity for development as a typical type of Broad-Band application. In respect of VoIP technique and standard, SIP becomes the dominating protocol because SIP is more opening, easier to extend, closer to Internet than the other protocols such as H.323 and MGCP. After many years of development since SIP was first proposed, SIP has become mature. People in telecom industry have formed the point of the view that the SIP product will dominate the future market of VoIP.The paper analyses the characteristic of SIP protocol and call flow, and researches the processing of SIP message. The paper also discusses the problem about multi-media system communication based on SIP protocol, which in the condition of NAT/FW and Internet net architecture and the environment of NGN. The solution of the problem...