SIP What is SIP? SIP stands for Session Initiation Protocol. Related Posts:SIP Trunk Cost ComparisonWhat does Future of SIP Trunking Look like?Why Are Businesses Switching to SIP?Related Articles: VoIP Industry to grow to $76.1 billion in 2015Microsoft Skype for Business SIP TrunkspricingVoice SMS SIPTrunkConfigure Free Switch with DID For Sale« Back to Glossary Index