The Research Of The SIP Protocol In IP Telephone Application

With the rapid development of computer network technology, network telephonewith the fastest developing speed, has become one of the key technologies in moderncommunication field, and has its unique advantage position. Session Initiation Protocol,is a kind of session initiation protocol, SIP for short. This protocol is used to create ormodify and terminate one or several people dialogue process. The Internet engineeringtask group claims that the protocol is a signaling control protocol on application layer,which is the important tool of realizing some network dialogues, and remoting somemultimedia conferences. The SIP protocol is considered to become the new favorite inthe3G in future, even extending to the VoIP field, because of its excellent properties,such as: the number is unique, the negotiation of the media parameter is convenient,and it’s easy to be expanded and so on.In the current network communication industry, it mostly follow three protocol ofH.323, MGCP, and the SIP. It’s generally based on H.323protocol for further analysisand research of SIP protocol, for how to realize such a process as that from registrationto creating a dialogue and initializing the session, and to initiating a call and alteringsession parameters, at last to the end of the call, and then elaborates the function thatshould be possessed in the network telephone. I have to simply plan the general stepsand requirements of the program design using a flow diagram as the form, at last realizethe programs using C++or C language based on the SIP nature, and explain andillustrate what process it should have on completing a network telephone call, finallysimulate some of the basic functions of the telephone network using software programs.I take my researching in the text mainly directed against the key technology of theSIP and combining with the practical application of the network telephone. Firstly,considering the current level of development of the SIP, I elaborate the researchbackground and contents; Then I introduce detailed definition, function, component andstructure of the message and protocol, and its calling process. Finally it’s the softwaredesign of the VoIP. In this part, I firstly introduce a complete VoIP communicationprocess, then introduce the oSIP protocol stack and its extended form eXoSIP, and adetailed description of the oSIP structure. Then, I elaborate the oSIP, RTP protocolimplementation process, the design flow of SIP UA module, and work flow of SIPserver module. In the end, I give the compiler steps of the software program usingVC++6.0in the Windows environment.