The protocols RTP (Real-time Transport Protocol), SIP (Session Initiation Protocol), H.323, and SRTP (Secure Real-time Transport Protocol) are commonly used in Voice over IP (VoIP) communications. RTP handles the transport of media streams, SIP manages call setup and control, H.323 is a standard for multimedia communication, and SRTP provides encryption for RTP. Therefore, the firewall rules for these protocols support VoIP.