Research And Implementation Of SIP-based VoIP Integrated-Mode Terminal

With the infrastructure of network with broad bandwidth implementation andrapid development of network interface technology, as well as universal contributionand broad application of enterprise LAN, there is much more attention took on EIM-based VoIP service. The Enterprise Instant Message (EIM) system cored with VoIPwill not only cut the cost on daily communication, but also provide lots of conveniencefor enterprise routine and will gradually become typical representation of stratagemsubstance and competence in the new-mode enterprises. Since there is very importantrealism meaning of research and implementation on connection of EIM system andVoIP related techniques.Design and development tenet of SIP-based VoIP integrated-mode terminal is tak-ing full advantages of existing PC and network source in EIM system, implementingSIP-based VoIP terminal application, instant message communication and VoIP hard-ware with USB interface. There are many good points of SIP-based VoIP integrated-mode terminal, such as easy to upgrade, plug and play and so on, which satisfy thedemand of enterprise routine in a economic and convenient method. Regarding tospeech processing, it used Voice Active Detection (VAD) in order to decrease the band-width took by VoIP communication, and Comfortable Noise Generation (CNG) so asto eliminate the uncomfortable feeling brought to VoIP terminal user due to VAD.The blueprint of SIP-based VoIP integrated-mode terminal adopted modulariza-tion and step-down design method. It selected TCP, UDP protocol as transmissionprotocol according to the di?erent requirement of signal communication and speechcommunication in the VoIP, so that the VoIP communication would be both reliableand real time. Considering the security of speech communication, it also introducedRTP/RTCP protocols as guarantee of the security of UDP transmission. It adoptedWindows multithreading synchronization technique dealing with the problem of syn-chronization among modules of network transmission, audio collection and play, cod-ing/decoding and others. The whole blueprint included scheme of VoIP hardwareterminal, which is according to status that PC has been the most popular and basico?cial equipment. The implementation of VoIP hardware terminal used USB inter-face in order to easily connect with computer, which realized a kind of low-cost VoIPhardware terminal.Speech quality test method of VoIP integrated-mode terminal adopted a new testmethod. It tested and computed the real-time network communication environmentinitially, then used the MOS test method as well as the result of the real-time networkcommunication environment to form a new method with both subjective and objective VoIP feasibility standard. The result of test revealed that SIP-based VoIP integrated-mode terminal implement speech communication function of SIP terminal successfully,with clear voice, small delay and easy to control the call process.The paper belongs to application paper, which is valuable on engineering creation.It worked on the basis of SIP-based VoIP techniques, and would help following researchon engineering reference.