Traditional telephony last about 100 years in use as the basic voice communication because of its reliability that satisfy the normal needs. Packet switching network, especially the Internet, which rapidly spread , attract more and more applications, because of its flexibility and efficiency. One of the most important applications is VoIP, which transmit voice in the same method of transmitting data, taking into account that voice is a real time application. Once we can transmit the voice over IP network, we do not need to route calls using the expensive and large central switches of PSTN, since we can route the calls in the same manner that we route data in IP network. This is the task of the soft switch; soft switch may seem to be the counterpart of central office or PBX of PSTN network. Finally, this project outlines the overall system of VoIP communication, and then show how to implement a whole telephone system based on IP protocols. The implementation of this project will improve the telephony service and management in (IUG).