A Research Of IP Telephone System Terminal Based On SIP Protocols

With the rapid development of the Internet technology, traditional applications over Internet have been gradually extended to multimedia applications, such as audio and video. It becomes more and more popular for people to communicate by telephone over Internet. VoIP has become one of the technologies which are caught most attention and improved most rapidly in the field of network. As a network researcher, I think it is imperative to work on the studying for VoIP technology. The author makes a introduction to a IP telephone system of the SIP protocol. In the paper, We discuss some technologies of Phone-to-Phone system comparing two signaling control protocols---H.323 and SIP. This paper describes the development process of PC-to-PC IP telephone system in detail. Five functions are implemented in this system: Firstly, collection and playing of voice; Secondly, compression and decompression of voice data; Thirdly,transportation of voice data on the network; fourthly, multi-connections among userscan be controlled; Fifthly, the voice communication and text communication are simultaneous. This system is based on TCP/IP, adopting C/S structure. It nuts on Windows 2000 operating systems and is achieved with VC ++6.0. SQL Server2000 is the database support. To control hardware. the system makes uses of low-grade audio functions. It adopts the UDP protocol to implement connectionless service. The application of multibuffer technology can guarantee the continuity and QoS of video transmission. Voice data's compression and decompression are implemented by ACM.At the same time, all operations can be executed at one time with multithreading.The system uses distributed control mode and realizes the intellectual clients.This is the significant innovation of this system, and it is important for further research about VoIP technology. Indicate through the analysis of performance, it is reasonable and practical to design ideas and methods showed in this thesis. And these are valuable for developing similar systems.