Voice over internet protocol (VoIP) sends voice communications over the internet, bypassing traditional phone lines or, public switched telephone network (PSTN). VoIP converts voice information into data and sends it over an internet connection.

On the other hand, session initiation protocol (SIP) is a signaling method for internet telephony. It’s used to set up, manage, and end a VoIP call. Using a SIP phone provider allows two IP phones to communicate using standard methods.

SIP trunking takes this a step further by allowing businesses to send voice and data communications, internally and externally, over the internet instead of a regular telephone network. It’s a departure from traditional VoIP applications which translate internal IP communications – as voice communications – over phone lines.