Research And Application Of VOIP Signaling Protocol Based On SoftSwitch

The next generation network is an open infrastructure, which can provide voice, data, video and multimedia services. The core technology of NGN is Softswitch, whose key function is call control and call connection.The signal is separated from media in Softswitch. Furthermore, it can provide new supplementary services. In Softswitch, the research of protocol about VOIP is one of the critical fields that is paid attention to by people.The key technology of the development of VOIP is signaling technology.The most widely application of signaling protocol is SIP, MGCP and H.248. As an important media control protocol, H.248 has inherited all advantages of the protocols before.It's convenient for interaction and expansion between them.Undoubtedly, H.248 protocol will play more important role in next generation network.In the thesis, firstly the concept of Softswitch technology is introduced, Function model is analysed on the basis of mSwitch structure in Utstarcom and corresponding issues are pointed out in Softswitch.Then, several signaling protocols are discussed, such as SIP, MGCP and H.248.Having analyzed the syntax, the entity, response code of VOIP protocol, we discuss all kinds of call procedure in detail and summarize their difference according to implementation in reality.Further, on the basis of thoroughly study about H.248's theory, we bring forward a design methodology about subscriber's access module of H.248 in Softswitch of Utstarcom.Using modularization design and driving thinking, adding the subscriber's access module in traditional adapter module of protocol, to make system finish basic call and supplementary services in H.248 terminals. In module, we design the relating data structure and state model about registration and call procedure. After designing the module in system, it's easy to maintain and expand relating services in future.At last, the test solution of H.248 module in Softswitch is provided. Several functions are verified, including registering on the call server and some basic call .The result proves: this system runs well.