By leveraging its IP PBX to handle calls using voice over IP (VoIP) and adding unified communications (UC) applications, enterprises can decrease costs, improve collaboration and ensure business continuity. But enterprises need to fully realize the security implications of extending their VoIP/UC network over untrusted networks. To extend VoIP/UC securely, there are a number of best practices that must be followed to prevent attacks and minimize risk. Some of these best practices can be borrowed from the data world but new VoIP/UC-specific security best practices must also be deployed. This white paper will look at the unique threats that target VoIP/UC networks and users, outline VoIP/UC security best practices, explore the shortcomings of existing security products in satisfying those best practices, and examine the requirements for a comprehensive VoIP/UC security solution.