Research And Realization Of SIP Server Based On Libosip2 In The Linux Environment

The appearance of VoIP has brought a revolutionary change to the traditional telecommunications network. Session Initiation Protocol (SIP) as a important protocol of VoIP, which appeared after the H.323 protocol, is replacing the place of H.323 in the VoIP field. In VoIP systems based on SIP, SIP server is the vital part.Libosip2 is an open source SIP library developed by the GNU. Its advantages are flexible, compact and efficient. However, because of lack of ease to use in the development of the SIP server, there was no mature SIP server based on this library.This issue describes the realization of SIP server based on libosip2 in the Linux environment. The main work is as follows:(1) Introduce the VoIP-related agreements, deeply study and introduce the SIP protocol standard RFC 3261. The standard is the latest standard about SIP protocol.(2) Analyze the source code and working mechanism of libosip2 in depth, through the analysis of source code, this issue found that in multi-threaded environment, as well as the implementation of a particular sequence, the server might access to the released memory space when releasing the transactions' resources. The implementation of these sequences is unlikely to occur, because the server requires long-term operation, so, it is a big risk. In this issue, solve these problems by increasing the number of mutex locks.(3) Based on the analysis of libosip2, realize the SIP server system based on libosip2 in the Linux environment. The system includes the registrar server, proxy server, redirect server and a series expansion of application functions, which include CRBT, voice mail, billing services and blacklist.(4) Built an experimental system with the UA for testing, analyze the experimental results, and compare the server with other similar products.