i had this same question and thought that if facetime works through wifi then it must be free overseas but calling to a different country would cost you a pretty penny!
see im not too sure im getting a little bit confused here. Obviously the WiFi is free but i heard that using facetime will cut your minutes allowance or if your on payg you would still get charged the standard minute rate?i still need to check my minutes but i cant 🙁
yes yes yes! i can confirm to everyone that facetime is totally FREE! and also if you activate facetime during a normal phone call, the minute facetime kicks in, it 'hangs' up the line connecting through the telephone network! it really is genius aint it 😀