The US National Security Agency (NSA) released guidance for securing Unified Communications/Voice and Video over IP Systems (VVoIP) The guide urges a security by design for these tools, detailed planning and deployment activities, and recommends continuous testing and maintenance. The guide is separated into four parts and provides for each of them mitigations and best practices to use implement. The agency also recommends implementing layer 2 protections, implementing authentication mechanisms for all UC/V VoIP connections and implementing an effective patch management process.”]
Source: https://securityaffairs.co/wordpress/119180/hacking/nsa-unified-communications-vvoip.html