Research And Realization For The SIP Server And Pickup Value-added Service

With the quick development of the network technology and the appearance of NGN,people want to communicate with each other in multimedia including voice, video, and data on the IP network.SIP (Session Initiation Protocol) is just an application layer signaling control protocol used to manage the multimedia communication session created on the IP network.SIP Server is located in the middle of the whole SIP architecture.It is mainly responsible for the processing and routing of SIP message,It play a very important role in the SIP system.This thesis first introduced the functions, hiberarchy, SIP message, session operation models of SIP and the usage of SIP in the NGN. SIP is concise, flexible and easy to expand, so it is favored by the industry and has broad prospects for application.And then, this thesis concluded the functions and system architecture of SIP Server. SIP stack is an important part of the SIP Server.The design and realization of SIP stack was provided through the research and comparison of SIP stack. "sluggard" strategy for decoding SIP message was adopted to enhance the efficiency and stability of SIP stack.The use of the callback mechanism made SIP stack very clear,flexible,easy to expand. Then the design of the SIP Server was provided with the actual project experience.The realization mechanism of Proxy Server, Redirect Server, Register, Location Server was concluded. Through a detailed analysis of the core modules of SIP Server, the realization of SIP Server was provided, the initialization and information handling processes of SIP Server was introduced.Finally, this thesis briefly introduced SIP value-added services, provided the model of IP telephony value-added business'realization based on SIP.And then, the design and singaling processes were provided integrated with specific value-added service named"Pickup". The test method and the actual test data were provided. Through analysis of the test data, the validity of the value-added business named"Pickup"was proved.