The Research And Design Of An Embedded VoIP System Based On SIP Protocol

Packet switch network technology and speech telecommunication technology has gained remarkable progress in recent years: various speech telecommunication technology were proposed and improved ,and the scale and transmission rate of packet switch network promoted,meanwhile they interacted with and influenced each other . Convenient, low in cost and easy to extend, the packet switch network based speech telecommunication is catching more and more interest from the people and sure will take the lead of the modern telecommunication technology .Therefore,it is of great value in theory and practice to implement an economical and practical VoIP system.This thesis introduces a VoIP system with up-to-date network transmitting protocols and codec,and elaborates on tentative research and design into the combination of VoIP system and embedded system.A VoIP system with practical significance is built in this thesis based on the analysis into current VoIP system in reference to the theory and technology of mainstream VoIP system, SIP and RTP protocols as well as CELP codecs. The system consists of two parts:SIP server and client. SIP server provides client with services such as proxy, NAT, register, session, Iocation,etc. ,while client communicates with SIP server to acquire the information of destination, and setup speech telecommunication with the help of SIP server. The construction and configuration of SIP server and the hardware and software of embedded client are the main concern of this thesis.The thesis details the configuration of SIP server and the design and implementation of client according to the requirement of the VoIP system .An open source SIP server OpenSIPS is deployed ,it is capable of providing stable service to SIP application in LAN .The hardware and software implementation of client include transplant of bootloader, the configuration of embedded operating system file system,and drivers of some device,as well as the program of communication client running both on embedded plat and PC.The test result indicates that the VoIP system proposed in this thesis takes advantage of muli-thread technology, speech processing technology and network technology to fulfill realtime communication on packet switch network.It functions well in client register, proxy, session, and IMS, and perform excellent in data compression, noise suppression to provide clear, smooth speech telecommunication with low delay. All the results above mean the anticipated target has been achieved.