The Research and Development of Embedded VoIP Gateway Based on IXP425
|Course||Communication and Information System|
|Keywords||VoIP SIP oSIP2/eXosip IXP425|
With the rapid development of computer technology, network transmission technology and digital signal processing technology, various real-time multimedia applications based IP packet switch network are widely in use. As a typical IP application, VoIP (Voice over IP) has challenge to PSTN telephone as more powerful functions, lower price and high flexibility. It also accords with the evolution trend of "networks merging" (including telephone network, data network and cable TV network).Signaling is one of the key technologies VoIP depends on. H.323 and SIP are the two presently most widely used signaling protocols in VoIP. H.323 occupies the mainstream of VoIP signaling currently. SIP is signaling protocols designed for an IP telephone, drawing on some Internet standards and protocols ideas, following compatibility and extend in style, supported traditional telephone network business. Interest in SIP increases progressively, because SIP is in accordance with the trend of VoIP and the future networks, with brief structure and close connection with internet. VoIP Gateway is the most important part of VoIP system. It can provide users with low-cost access to VoIP service and various VoIP-based value-added services. This paper analyzed and studied principles of VoIP communication systems, system components, communication protocols (H.323 and SIP), describes the role of SIP network elements and the composition and function the of SIP message. It gave a VoIP gateway program design and implementation process in the embedded Linux based on oSIP protocol stack.IXP425 is high-performance network processor of Intel Corporation in order to meet the embedded network design. Platform based on IXP425 processor provided the Ethernet port, serial port and so on, which Redboot and ARM embedded Linux operating system transplanted on. In application program development used the best open source SIP protocol stack Osip2/eXosip and developed the VoIP gateway user agent client and user agent server.The programme could achieve the system function by the test results.