Threats Analysis on VoIP System

VoIP System is popular as compare Public Switching Telephone System (PSTN) because of its economical and rich multimedia feature.This popularity increases VoIP subscription as well threats on  it. It is equally important to address these threats to safe guard VoIP system. In this paper ,We have attempt to classify all threats  as a confidentility,Integrity,Avability and proposed a guideline to mitigate it