Based On Sip Voip Terminal Equipment

With the fast development of networks technologies and audio compression technologies, the applications of VoIP are becoming wider. As one of the most important control (signaling) protocols of VoIP system, SIP is being studied and developed more and more. According to these, this thesis describes a design and implementation of VoIP terminal device based on SIP and makes a study on SIP messages compression technology.In the thesis, the background and development status of VoIP is summed up, the principle, key technology, standards and protocols of VoIP are introduced as well. On the basis of exploring, an implementation of VoIP terminal device is given, and an archetypal IP phone with SIP UA function is designed and implemented. With this device an experimental LAN VoIP system is built up in order to discuss and validate VoIP theory from engineering aspect. The function of SIP in creating and supporting sessions is also proved to be effective. According to the development trend of network technology, the compression technology of SIP messages is studied, and a method to increase QoS by ensuring the transmission of control (signaling) messages is given.