Flash my iphone
How can I switch my iPhone from sprint to AT&T
Apple Event: May 7th at 7 am PT
How can I switch my iPhone from sprint to AT&T
Details on carrier unlocking > How to unlock your iPhone for use with a different carrier - Apple Support
Details on carrier unlocking > How to unlock your iPhone for use with a different carrier - Apple Support
Ensure that your iPhone is carrier unlocked. Then insert the AT&T SIM card in your iPhone and it is complete. The issue here is that we do not know which model iPhone you are using. Is your iPhone capable of working on CDMA (Sprint) and GSM (AT&T) service? You have kept this information a secret so a complete answer is difficult to present at this time.
Axel F.
Flash my iphone