Voice over IP (VoIP) presents totally different challenges than a public switched telephone network (PSTN). It runs on the web and inherits many challenges for VoIP service providers on a way to secure VoIP system. Until now, security has been overshadowed by the attractiveness of VoIP technology. Security Risks Meanwhile, VoIP traffic remains on networks that aren't sufficiently protected. This infrastructure includes personal branch exchange systems; gateways; proxy, registrar and locator servers, and phones. every VoIP component is available and accessible over the information network. Therefore, before deploying VoIP system you need to remember its security risks and also the countermeasures.