I'm not sure what this thread is about. Isn't an unlocked phone basically the same as a sim free phone. IF I did have a sim free phone and I wanted to us ATT, would I need an ATT sim card in a sim free phone. I have the ATT IP8 (fully paid). A few days ago I requested it to be unlocked and in less than 24 hours, ATT unlocked. I know with this phone now I can go overseas, pickup a local sim card and be good to go.
The thing I don't know is if my unlocked IP8 could EVER be used with Verizon or anyother CDMA network.
iPhones purchased from Apple directly are all unlocked. But of those unlocked models there are two kinds. AT&T and T-Mobile models are only GSM unlocked, they can be used on any networks runs GSM but not CDMA networks. Verizon and Sprint models are both GSM & CDMA unlocked, hence can be used on virtually any network worldwide.