Inside The VoIP Internet Phone
Source: VoIP Providers List
A VoIP Internet phone, unlike a conventional phone, sends voice signals over the Internet. These signals bypass the Public Switched Telephone Network (PSTN) when the call is made from one Internet phone to another and is considered broadband phone service. However, when the call is made from an Internet phone to a conventional phone, the voice signals journey part of the way over regular phone lines.