A Design Based On The Ims Sip Stack User Agent Module

The main characteristics of the third generation mobile system provide abundant mobile multimedia service, including data, voice, image and video etc.The IP multimedia subsystem(IMS) which is introduced in 3GPP UMTS specification is designed to support the mobile multimedia service. In Release 5, IMS provided a series of solution of mobile networks'IP multimedia service. IMS is located in the 3G core network, which built on the packet domain.Session Initiate Protocol (SIP) is accepted in IMS as the session control signaling protocol. IMS core based on the SIP protocol architecture and use SIP message to control the session, to create, manage and terminate all kinds of multimedia service. All kinds of terminals can establish a Peer-to-Peer IP communication and get the services they required. IMS also provide the key functions of multimedia services, such as register, account, session control, carrier control, media negotiation and safety, etc. It is the base of converge for multi-services, can support voice, data and multimedia applications. With the development of Fixed Mobile Convergence (FMC), IMS is the most important phase in NGN (the Next generation network).Firstly, the paper introduces UTStarcom SIP Stack(USIP) designment and implement in 3GPP IMS, and describes the designment and implement of User Agent(UA) module which based on the USIP. In this paper,which introduces the IMS frame and the demand of Session Initiate Protocol. On the basis of these, we designed the USIP frame and relative functions. The paper particularizes USIP performance data,and expects the future research of USIP.USIP User Agent designment is a good reference for protocols of based on the IP,which is help for understand the IMS system.At last,summarize the paper,point out all the shortage in USIP and its User Agent module,and raise the respects for USIP research.