Research And Implementation Of VoIP Monitor System

Since the birth of VoIP, there has been a rising demand for transmission of multimedia information over the IP network. As the traditional PSTN network has been unable to meet the needs of modern communications, and due to the advantages of low cost and the good quality and performance of communications, VoIP communications market is expanding rapidly. Now the control of VoIP is not as easy as PSTN, many illegal telecommunication operators who operate unauthorized landing gateways to provide VoIP service, which bring about the destruction of the telecommunications market order. And because of the non-traceability of VoIP, the use of VoIP in illegal activities also increased. Therefore, the demand of the national security sector and carriers for the VoIP monitoring system is huge and pressing.There are two standard signaling protocols: H.323 and SIP in the VoIP system. Domestic VoIP market currently mainly based on the H.323 protocol to build VoIP networks, but with the network development and integration trends, SIP protocol will replace H.323 protocol to become main stream. While there are many non-standard VoIP signaling protocols, such as Skype and other private protocols, with the further growth of Internet users and exchange needs, the standard protocols will become the first choice for manufacturers.The VoIP monitoring system is designed to the demand of a city Public Security Bureau, which mainly focused on realization of voice monitoring functions. The system can support the resolution of standard H.323 and SIP signaling protocols, through which we can abstract the calling and called party information and media channel information, and accordingly we can capture the voice packets. That is to say we establish the association of the caller's information and the content of conversation. This monitoring system is not only able to complete VoIP network traffic monitoring, recording the details of a single call information, record the content of conversation, but also is able to disturb the ongoing conversations by constructing voice packets to prevent the spread of illegal information.The system can take advantage of communications information, statistics calculus the may exist gateways of monitored network, gateway's business traffic and types of information. So the monitoring system can be deployed at the gateway or proxy server to monitor VoIP communications of the area. In Chapter V there brings about an anti-spit solution based on statistical characteristics of signals. At present most of the anti-voice programs are based on trust mechanism, which does not make good use of a large number of useful information between the interactive processes of exchanging signals. In this paper, we make use of VoIP monitoring system to record every single call's detail information, carry out statistical analysis of all the VoIP traffic flowing into the area, bring about a solution based on the statistics of each caller's calling pattern.