SIP And QOS-based Development And Application Of VOIP

With the rapid development of the Internet, many integrated services use IP networks to achieve. The proposal of VOIP technology makes data communication by network gradually be integrated into the traditional voice business. Using Session Initiation Protocol to develop telephone network, which meets the needs of multi-media session on IP network, and add quality of service to guarantee the voice quality of Internet phone. Therefore, Using Session Initiation Protocol and the quality of services to develop Internet telephone can realize cheap voice services with the assurance of voice quality.SIP-based development of VOIP has a clear structure,which can be expanded. The business-class SIP protocol stack RADVATION and Slic processor can convert ordinary analog telephone signals to IP network packets , thus achieving voice network transmission. When the network meets congestion or a transmission error, the voice packet will result in delay, jitter or loss which lead to seriously affecting voice quality. So QOS (quality of service) of the VOIP application is also vital. The provision of quality of service,which usually uses in VOIP, is RSVP. But if router does not support RSVP, it is difficult to guarantee the quality of service. Therefore, in the realization of VOIP, especially VOIP gateway, a differentiated service model, a lot of strategys can be applied to meet the service quality, which can guarantee better transmission quality, when the network situation is not very good circumstances. Test results show that RADVATION protocol stack meets the requirements, and a certain QOS strategy makes the voice quality be markedly improved.Using RFC3261 as reference to the whole system , combining with user requirement, adding the concept of QOS, design a VOIP gateway to ensure voice quality. Because the signal transmission is based on SIP, the system has a good expansibility, and in accordance with the requirement of users, re-write the SIP state machine and telephone action state, allowing system operate as ordinary telephone. Finally, the test demonstrates that QOS greatly improves voice quality of service of the system, and it can be normal voice communications when bandwidth of network is restriction.