The Design And Implementation Of A Solution To Traverse NAT With UPnP In SIP Switch System

VoIP(Voice over Internet Protocol) is an IP-based telephone,and the introduction of value-added services technology.The VoIP biggest superiority is can widely use Internet and the global IP interconnection environment,provides are more than the traditional service,a better service.It is also the current hot Internet applications topic.SIP as a protocol important agreement NGN,is widely used in multimedia communication services such as VoIP,SIP,but in itself does not support SIP signaling and media flow through the firewall and NAT.The large-scale VoIP applications will greatly increase the demand for IP addresses,VoIP currently use the main NAT address the lack of technology to solve problems,it is followed through the NAT.The technical problems hampered the SP and operators benefit from VoIP.NAT is carried out through the biggest obstacle to the VoIP business,there is an urgent need to be resolved.This article first analyzes the SIP-based VoIP system related to the agreement,introduced a firewall with NAT and firewall under Linux,as well as the realization of the NAT way,and introduced the industry through several NAT solution.This paper gives an advantage of UPnP to achieve SIP NAT through the program and to achieve.The realization of the program into the SIP through NAT,UPnP assisted by the necessary process and a SIP and UPnP with the work of the flow chart of the state machine not only be able to make SIP signaling smoothly through the NAT, can also dynamically based on changes in the network To ensure continued through.In this paper, follow the requirements of software engineering,the program had a functional testing, performance testing and so on.Research and practice show that the plan put forward by an effective solution to the typical SIP through the NAT issues for large-scale VoIP applications and provides a means to help.