Way back when, you needed a telephone to make phone calls. With the advent of Internet-based VoIP calling, all you need is to be able to go online and the world is at your beck and call. While there are several different ways to make calls via the Internet, they each seem to come with their own set of limitations. Whether it's a commercial service where you pay a monthly service fee like Vonage, or a system like Skype where you can call computer-to-computer for free but have to pay when talking to somebody on a telephone, there's always something.
EvaPhone lets you make free computer-to-phone calls domestically and internationally. All you need is a web browser, a relatively recent version of the Flash plugin, and a microphone and headphones. You don't even have to create an account or log in. Your phone call is limited in length, depending on the destination you're calling. These time limits vary by country and location, but I suppose at the price–did we mention it's free?–you can't complain too loudly.
Needless to say, these folks would love to have you upgrade to their paid service, which removes time- and other restrictions, but there's no reason why you can't continue to enjoy their free offering.