The National Security Agency has shared mitigations and best practices that systems administrators should follow when securing Unified Communications (UC) and Voice and Video over IP (VVoIP) call-processing systems. UC and VVoIP are call-processing systems used in enterprise environments for various purposes, from video conferencing to instant messaging and project collaboration. The agency also warned companies to use self-hosted DNS-over-HTTPS (DoH) resolvers to block DNS traffic eavesdropping and manipulation attempts.
Source: https://www.bleepingcomputer.com/news/security/nsa-shares-guidance-on-securing-voice-video-communications/