- Cisco MGCP: Media Gateway Control Protocol
- H.225: Call Signaling and RAS in H.323 VOIP Architecture
- H.235: Security and encryption for H.323 (and other H.245-based) multimedia terminals
- H.245: Control Protocol for Multimedia Communication
- H.323: ITU-T VOIP Protocols Overview
- Megaco/H.248: Media Gateway Control Protocol
- NCS: Network-Based Call Signaling Protocol
- SAP (v1 & v2): Session Announcement Protocol
- SCCP: SS7 Signalling Connection Control Part
- SDP: Session Description Protocol
- SIP: Session Initiation Protocol
- T.120: Multipoint Data Conferencing and Real Time Communication Protocols (T.121, T.122, T.123, T.124, T.125, T.126, T.127)
