Since the beginning of telecommunication, phones have used 'circuit-switched technology' to send and receive calls. This technology uses hard phone lines to transmit calls from one telephone to another. The limitation with circuit-switched technology is that it requires a significant amount of bandwidth for each call, and it only supports limited types of calls (i.e. telephone to telephone/fax/modem). The hardware needed to run traditional circuit-switched networks is very expensive. The higher cost of the hardware and the inefficiencies of using dedicated bandwidth for individual calls has caused many telephone companies to use parts of the Internet to connect PSTN calls. You may have already received or made calls using VoIP technology without knowing it.

VoIP stands for Voice Over Internet Protocol, which is the process of using the internet to transmit phone calls. The voice stream is broken down into packets, compressed, and sent toward its final destination by various routes as opposed to establishing a 'permanent' connection for the duration of the call.

VoIP converts the sound of your voice into data and uses Internet Protocol to send that data.