A clear, lucid article on VoIP security (or, bad stuff that can happen to that fancy new phone on your desk that plugs into the network instead of the old phone jack). Written by one of the many vendors who offer solutions.
Summary:
• VoIP DoS attacks
• Spam over Internet Telephony (SPIT)
• VoIP service theft
• SIP registration hijacking
• Eavesdropping
• VoIP directory harvesting
• Voice Phishing, or Vishing
"WatchGuard advices all businesses using VoIP systems to review their perimeter and VoIP security." (more)
Additional solution vendors:
• Sipera
• Radware
• VoIP Security Buyer's Guide
FREE VoIP security information:
• Mark Collier's VoIP Security Blog
• Blue Box: The VoIP Security Podcast
• Security Considerations for Voice Over IP Systems
