Many VoIP software clients include a service that lets you call regular telephones. With your Internet-connected PC, you use the software to dial a number, and the telephone you're calling rings just like it would for any call. Because it takes special equipment for your call to get to the telephone, there is usually a per-minute charge. You will need to open an account and give your credit card number to the service provider. On the plus side, rates are very cheap for long-distance calls, although local calls may not be as cost-effective.

You're probably already using phone-to-phone VoIP and don't even realize it. Many phone companies have switched from using traditional, analog, long-distance lines to digital, IP connections during the past few years. When you pick up your phone and dial a long-distance number, there's a good chance your call will go through a VoIP adapter somewhere within the phone-company infrastructure.