The Study And Development Of SIP Stack

SIP was originally developed for initiation of multimedia sessions. It is currently receiving the most attention in the construction of VoIP system. To develop the stack based on SIP, for the purpose of fitting it for the telephony services, is the hotpot now.In this paper, by researching two implementations of SIP protocol,one named OSIP and the other named EXOSIP, an architecture of telephony-communication with SIP protocol is presented. Based on the architecture, new SIP protocol stack is designed for the purpose of developing IP telephone services, the structure of which has integrated more modules of communication on Internet than the original. Especially, the calling process control is separated as a single module, and adequate interfaces are supplied for the telephone services. So that applications of VoIP can be constructed more easily and rapidly. Additionally, the timer management of network applications is introduced to improve the network performance of the new stack.At last, series of experiments have been made in the LAN environment, which has applied an element system of VoIP. The results show the validity and compatibility of the new stack, which is effective to build a calling application.