| With the development of electronics and communication technologies, the performance of routers has been greatly enhanced that they can provide Category of Service (CoS) except for traditional data transfer. Further, SDH/SONET can provide high-speed swift physical links among different nodes. Thus, it becomes possible to transfer voice data through Internet, and VOIP (Voice over IP) is produced as the consequence of the enhancement of such technologies. Compared with conventional telephones, VOIP offers better services for customers with the widespread utilization of Internet resources. This dissertation delivers in-depth details about how to design and implement a visual VOIP terminal facility based on SIP protocols.The background and development history of VOIP as well as the fundamental theories, key technologies and the SIP protocol are introduced. Then, the VOIP network frame, VOIP network protocols, VOIP systematic facilities and important elements concerning business procedures are also investigated. Next, we investigate the approaches and procedures to set up communications with SIP protocols, and the major theory, constituents and key technologies of the SIP terminal facilities.The dissertation also presents the design and implementation of a basic local network, in which a visual VOIP terminal with QoS function is established by means of a direct communication method.Finally, the SIP protocol and H.323 protocol are compared, and the advantages for the adoption of SIP are analyzed. |
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