VoIP & SIP Difinitions, Terms and Acronyms Explained Understand VoIP and business calling terms: fast, clear, and jargon-free. ACD (average call duration) AHT (Average Handle Time) ASA (Average Speed of Answer) DTMF (Dual-Tone Multi-Frequency): Definition and How It Works G.711: What It Means in VoIP? Jitter MOS (Mean Opinion Score): Definition, Ranges, and How to Improve VoIP Call Quality PBX (Private Branch Exchange) Benefits and Features RTP (Real-time Transport Protocol) SBC (Session Border Controller) SIP (Session Initiation Protocol): Definition, How It Works, and SIP Trunking SIP channel UDP (User Datagram Protocol) VoIP