Design And Implementation Of Embedded Voip System Based On SIP

With the development of communication and network technology, SIP has been concerned more and more for its simplicity and flexibility, which gradually replaces H.323protocol and becomes the core VoIP signaling protocol. Meanwhile, applications of embedded system have extended from industry control system to consumer electronics with the development of embedded technology. The combination of embedded technology and VoIP technology has been paid more and more attentions, which is the current research focus. Therefore, we design and implement an economical and practical VoIP system, which is of great value in theory and practice.The system consists of VoIP parts:SIP server and client. SIP server provides client with services such as proxy, register, session, location, etc. while client communicates with SIP server to acquire the information of destination and setup speech telecommunication with the help of SIP server.This paper introduces the basic communication theory of VoIP, the functional structure of the SIP, the message mechanism of the SIP, etc. The paper introduces the hardware and software of embedded VoIP terminal, we adopt S3C2440A ARM9chip as core controller and embeded Linux operating system as development platform. The Linphone is transplanted as the terminal application software, which is an open-source Linux software and used widely. The paper analyzes the development principle of Linux drivers and introduces the design and implementation process of audio drive that based on the OSS audio system. The paper introduce the process of building a VoIP system that based on the Elastix server. Finally, we test the whole system functions in the LAN.The test results show that the design of the Embedded VoIP system based on SIP is practicable.