The Realization Of The Voip Gateway And Noise Suppression Delay Control Technology

During a long time of period, VOIP has become a hot topic in China's telecom industry after heat discussion of future development direction of voice technology. Lots of experts believe that VOIP is the development direction of future voice technology. Therefore, the meaning and purpose of China's IP phone market opening is that, breaking the monopoly and bringing about competition; improving the reform and adjustment of telecom fee structure; accelerating market competition and bringing the competition mechanism into the long distance call market; promoting China's Internet development and tranditional network's reconstruction;stimunating the increase of in domestic comsumption market.The commercial IP phone network is composed of IP phone Gateway, Gatekeeper, supporting system, telephone network and IP network. The telephone network can be interoperated with IP network by the Gateway, Gatekeeper and supporting system in the commercial IP network architecture. Meanwhile, the architecture utilizes the IP resource with the highest efficiency and implements the interoperability of tranditional telephone business between the two different kinds of network structures, on the IP network's predominance in the technology and economic fields.This paper introduces the basic architecture of present VoIP and relative standards it should conform to. It also gives a thorough analysis on several vital and sensitive problems such as delay and noise. Moreover, it constructs the core device in VoIP,the IP gateway,by using the AG2000 voice card produced by NMS corporation. It can provide many functions: the conversion between transfer formats, the conversion between communication protocols, the conversion between analog signals and digital signals, the conversion of control commands, real time audio code/decode, IP call control, control of RTP/RTCP, call detail logs, accounting and some of gatekeeper's functions such as address tansfer/search..It can satisfy the VoIP application demand at enterprise level and then performs an adjustment test according the vital factors bringing big affection to the quality of voice, such as voice quality and delay of different encoding styles, packaging capacity and delay, echo cacellation algorithm and digital voice mixture algorithm.Along with the development of the technology, all factors to affect VoIP must be overcome. We believe that VoIP take place of conventional audio transfers manner and bring great benefit for our human being.