Research And Implement Of VoIP Gateway Function Based On OSIP Stack

VoIP(Voice over IP) is a one of research hotsopts of NGN(Next Generation Net) with very wide application space. It transmits the vocal data in grouping, and can provide innovative comprehensive operations and functions. One of the key techniques of its development is the signal technique. SIP(Session Initiation Protocol) protocol is one signal protocol advanced aiming at IP telephone, and it adds the Qos(Quality of Service) requirement. It adopts many a design ideology of the internet criteria and agreement, and follows the principle of compatibility and extensiveness. It can support the various operation of the traditional public telephone net. Since SIP system always works in an open and complicated network, SIP net elements and SIP information may be confronted with various safety threats and attacks.The oSIP(Opensource Session Initiation Protocol) protocol stack is introduced into the embedded situation in the dissertation, enabling the gateway the mutual operation between the gateway and other network equipment can also get improved. The employment of oSIP protocol stack successfully realizes the new operation function of the gateway. By means of the encryption techniques and digest authentication in registering server, the communication safety of the gateway in the network can be ensured.First, the dissertation introduces the principle and technique of VoIP, analyzes VoIP gateway functions in the network. Second, analyzes the functions of each SIP network element, the structure and functions of SIP message, and how SIP message come into being and it is parsed by studying the oSIP stack. Later, introduces the structure of gateway hardware, establish each software module in application layer and reciprocity mechanism under considering hardware resources. Finally, realize the gateway functions, such as calling transfer, encryption, digest -authentication. the rationality of design blue print and exploitation procedure are validated by testingThe calling transfer function of the gateway not only satisfy the demand of market, but also boost competition capability. Realizing the encryption not only ensure the security of the network communications, but also enable the gateway to serve customers well.