Design And Implementation Of VoIP Gateway Software Based On VxWorks System

In recent twenty years, under the premise of the continuous development of technology, Internet world get rapid development, making us can connected to the Internet in any corner of the world. At the same time, China’s Internet is constantly expanding.And real time communication technology got a wide range of applications because of the popularity of the Internet, Thereinto,VoIP technology is an emerging technology of the real time communication, that people can making voice communication more conveniently by transmiting voice data over the Internet.Before the widely used of network,most people use PSTN which is circuit switched. Under the accumulation of many years, PSTN network worldwide, and the PSTN will continue to occupy a large proportion in the means of communication for a long time. In the actual situation, the research and development of a device whice can connect the PSTN and IP network has become inevitable.Based on the above viewpoint, this thesis puts forward a design scheme of a gateway equipment, which can effectively communicate the PSTN network and IP network, so that the two network users can communicate with voice.The hardware and software of the gateway equipment is designed in this thesis. The hardware part includes microprocessor, voice AD/DA conversion chip, voice codec chip, etc.. Software system design uses the modular program, mainly contains the voice processing module, the signal conversion module and the Ethernet processing module and so on. The design and implementation of software system is the emphasis of this thesis.Software system with powerful function of IXP425 processor chip as the core,using embedded Vx Works as the underlying operating system, the development of content including voice coding and decoding, design and implementation of Signaling conversion, Ethernet transmission realization.After the development and design, the gateway device realized the following functions: analog voice acquisition, coding and inverse process; voice coding type conversion; conversion of PSTN and IP side signaling; signaling and voice data in the network transmission.At last, the performance of the gateway is tested according to the design goal. The test results verify the correctness of the design scheme and the development process of Vo IP gateway based on Vx Works system.