Free Skype Calls
The vast majority of Wifi Phones on the market in the United States today use Skype. Skype is a voice over IP (VOIP) service, which basically means you can talk to people using the Internet. Skype is famous for its free voice-to-voice calls and relatively cheap calls to standard phones. WiFi phones using Skype can make calls to other Skype users for free, just as if they were using the Skype client on a computer. The difference? A hand-sized WiFi phone is a little easier to carry around than your computer.
Cheap Regular Phone Calls
Can't get all your friends to switch to their computers for all their phone calls? Fair enough. WiFi phones can be used to call conventional phones too. For $30 a year, you get unlimited calls in the United States and Canada; international calls have separate rates, which are typically (but not always) lower than cell or landline rates.