The Research Of VoIP Systems Based On SIP And Implentation Of VoIP Terminal

Voice over IP(VoIP) is the technology which uses the IP network as the carrier of real time vocal dataflow, to make a communication connection between computers, traditional telephones and both of them. It can also provide the value increment service based on the basic structure of VoIP.In this thesis, research has been carried on in several aspects such as network structure of VoIP, protocol layers of VoIP, signaling control protocols and the LAN VoIP system based on SIP. And then, the VoIP terminal device is designed and tested in the environment of the experimental LAN VoIP system.Research has been focused on the two different signaling protocols: H.323 and SIP, and then a solution based on SIP is provided, and proved to be effective in the experimental LAN VoIP system.Also the very important factor Quality of Service(QoS) is investigated, the different QoS supports in the IP packet switch network are given and analyzed, including Intr-Serv mode and related RSVP and Diff-Serv QoS mode. The architecture to guarantee the end-to-end QoS over the different protocols and different network domains in transmitting the real time vocal data flow is provided. Then the synergic solution to provide the better QoS over the currently Best-Effort network is given and evaluated.