Research And Implementation Between SIP And H.323 Protocol In Softswitch Network

H.323 networks transmitted by IP network system has been widely used before the SIP network appeared. So it is important to take into account the interworking between SIP networks and the H.323 network.At present, the mainstream technology standard of VoIP system is ITU-T recommendation H.323 protocol in our country. This standard has gained very far-flung application. Because of merits of the technology such as flexibility extensibility of the SIP, VoIP system based on SIP protocol has occupied more and more market share. For the two multimedia transmission system, they can not compatible each other because of the inherent differences between SIP and H.323. However, considering of the problems of cost and invest, that SIP absolutely substitute for H.323 immediately is impossible. Therefore, the study of interworking between SIP and h.323 protocol is very significant.In the first place, the present key technology, development and foreground of VoIP system, the next generation network and softswitch's structure, function and the main protocol they used are introduced; the SIP and H.323 protocol stack, structure and call process are deeply analyzed; the characteristic of SIP with H.323 protocol is Compare each other. Above the basis to study interworking between two protocols, the problems such as address resolving and mapping, information mapping, call sequence mapping, the negotiation of media capability which are produced in the process of the two protocol interworking and the state diagram of the interworking is analyzed. Based on the above study, the InterWorking Function's SDL flow chart is designed. Finally, SIP terminal to H.323 terminal and H.323 terminal to SIP terminal launched call model is built to simulate the interworking of two protocols. Test results prove that the scheme is reasonable and practicable.