Research And Implemention Of VoIP Client Based On SIP Signaling Protocol

Internet offers people an easy way to transfer data. And with the development of information evolution and telecom industry, value added services are stimulated. It is possible now that transfer voice data through Internet. It is Internet Phone. It becomes a hot spot. Internet Phone attracts more and more attentions for its virtues like low fees and low maintain cost. At present, more and more people adopt Internet Phone to communicate with others. Internet Terminal is demanding. Not only computer based terminals, but also low cost terminals are needed by people. So it has practical sense investigating Internet Phone Terminal.Internet Phone technology is called VoIP technology, viz. Voice over Internet Protocol. It is not a single but a system integrated with several technologies constructing communication network, including Signaling Protocol, Voice Codec, Media Transport and Gateway Control. SIP, Session Initiation Protocol, is one of the Signaling Protocols. It is in application layer. Compared with another Signaling Protocol H.323, it has virtues such as more simple in call flow and text messages. And it is taken into use by more and more equipment provider.The main object is trying to implement SIP stack. Then, design a prototype of voip client based on the stack, which can exchange sip messages with other clients.It this article, firstly, on the base of research of SIP protocol and oSIP, a set of API functions was designed to implement SIP UA functions. Then, a Internet Phone Terminal was designed. Motorola ColdFire 5272 was used to construct target system. uClinux was used as OS. oSIP and the API sets was used to implement SIP. OKI ML7074 was used to implement Voice Codec. At last, an experiment was constructed to validate the terminal functions. At the bottom, summary was bought up.