Abstract: “Voice over IP is one of the quickest developing Internet services and slowly replaces traditional telephony. However, while moving telephony to the public IP platform broadens its service capabilities, some security problems may occur. It is because the amount of threats existing in IP networks is much bigger than in case of traditional telephone networks. Therefore security challenges of VoIP public network are considered in this work in detail. Full security analysis is performed that covers m”

Keywords: VoIP, Network Security, vulnerability , network architecture , threats.