VoIP technology is an extremely important application in Next Generation Network (NGN).Nowadays, the system of controlling signal including H.323 protocol series of ITU-T and SIP protocol of IETF is acceptable. The H.323 protocol defines the multimedia communication protocol and procedure based on Internet or other packet network without service quality assurance. IP Call Center, a combination of VoIP technology and Call Center technology, has many advantages, for example, low in price, simple and open, and will be the trend in the development of Call Center. Now more and more commercial and scientific research institutions have engaged in the research and development of IP Call Center.Call Center based on H.323 protocols is one of the promising applications, which has changed the traditional Call Center. The new one include all kinds of devices, such as gatekeeper, auto-call-distributor, CTI-Server, IP-IVR, agent, database. The system's advantage of low-price and distributed topologic...更多al structure attracts more and more enterprise and people.Firstly, the paper introduces the background of the object which has done by author and the tasks done by author. Then, it presents ITU-T's H.323 protocol stack, additional businesses, architecture of H.323 and other VOIP protocols simply.
