  VoIP applications are emerging today as an important component in business
and communication industry. In this paper, we address the intrusion detection
and prevention in VoIP networks and describe how a conceptual solution based on
the Bayes inference approach can be used to reinforce the existent security
mechanisms. Our approach is based on network monitoring and analyzing of the
VoIP-specific traffic. We give a detailed example on attack detection using the
SIP signaling protocol.
