| With the popularity and development of Internet technology and multimedia, it's becoming possible to combine with voice, data, video into one single network. VoIP(Voice over IP) which is a promising competitor in voice communication field comes into being with those needs and make a huge development. It can advance the using rate of line, cut cost and realize many value-added services. Even though the quality of VoIP is still need to be improved, we can also believe that with the fast development of technology, VoIP technology will have a prospective future.SIP(Session Initiation Protocol) is one of application-layer control signaling protocols in VoIP technology proposed by IETF(Internet Engineering Task Force). Becase of its simply and agility, H.323 protocol is replaced by SIP protocol gradually. SIP can easily extend, this can advantage in developing value-add services and conference calls. Now years, SIP protocol gets more and more attention and progress, we need to research on it.At the beginning of this thesis, we present the background, key technology and related protocols of SIP. Next, we detail definitions, functions, components, messages and structures of SIP. Furthermore, with the advanced embedded system technology, we aim to implement a UA(User Agent) in embedded system. We also design the high-level framework of the system, divide it into modules and implement one by one.At last, we do tests about the system and make a conclusion to meet the anticipation.This system which introduced by the thesis is applied and launched to market by a company, and gain the great economic benefits. |
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