VoIP, or voice over internet protocol, is a technology that allows users to make phone calls using a broadband internet connection rather than a traditional phone line. It converts the analog voice signal into digital data packets that can be transmitted over the internet. Common VoIP protocols include RTP for transmitting audio and video streams, SIP for initiating calls, and SDP for describing multimedia sessions. VoIP provides benefits like cheaper calls and improved accessibility compared to traditional phone networks, and is considered the future of telecommunications.