Use a Calling App Wifi
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Rebtel is ingenious, a service that can either set up a free, Skype-like call over wifi or cellular 3G networks, or, if those are unavailable, route international calls through a local number. The latter option does require access to a landline, or an unlocked "world phone" and you'll be charged for the local call. Rebtel's international calling rates are showstoppers, though, such as 1.5 cents per minute to the United States.