| SIP (Session Initiation Protocol) is the IETF(The Internet Engineering Task Force) proposed framework for a new generation of multimedia communication signaling protocol, the business logic to achieve functional flexibility, easy to support wired and wireless networks, seamless access to and become the core of NGN protocols. It is the application layer signaling control protocol is mainly used in IP network traffic when the media session management. Now widely used in wireless communications, soft switching, NGN and 3G systems.As the mobile communications and Internet technology continues to evolve, mobile phones can already connect to the Internet, but subject to traffic and tariff restrictions, the Internet can not be a strong function of the phone given full play. The emergence of wireless local area networks and access points growing, giving mobile phones to a broad development prospects.In this paper, mobile phones with SIP to achieve the key issues SIP phones and SIP servers, in-depth study in the WLAN SIP User Agent Client and SIP User Agent Server, two key modules of the core processing logic and implementation method for the eventual realization of transmission created the conditions for SIP messages. This in-depth study of the SIP-layered structure, function entities, message syntax, the basic work processes, the main extension mechanism, as well as SIP on J2ME platform in development mode. Analyzing the communication model of SIP User Agent Client and SIP User Agent Server by using JSR180(Java Specification Requests). Finally completed the SIP User Agent Client and SIP User Agent Server communication between the removal and the establishment of the session, as well as delivery of features such as SIP messages. Through the use of SIP user terminal testing to verify that the SIP User Agent Client and server communication consistency. SIP multimedia services to support a common terminal, through this system can form a complete SIP-based messaging system. |
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