Is my iPhone considered unlocked?

[JHoffy1]

I bought an iPhone 4 let year on ATT and used it until I upgraded to the 4S.

I then sold my iPhone on Ebay as unlocked.
The person that purchased my iPhone is trying to use it on t-mobile and is telling me I sold him an unlocked iPhone4.

Is this true? I though once a phone is unlocked on AT&T and used for a year, it is always unlocked.

Was I correct in selling the phone as unlocked?

Thanks in advance.

Jon

[Simon]

Do you mean the person you sold it to said it is a locked iPhone 4?

ATT iPhone 4's are never unlocked. A gevey sim normally has to be used as a unlock.

[JHoffy1]

Do you mean the person you sold it to said it is a locked iPhone 4?

ATT iPhone 4's are never unlocked. A gevey sim normally has to be used as a unlock.

Can you please explain to me the procedure to get a iPhone working on T-Mobile thank you

[GnatGoSplat]

You owe buyer a refund.

The only way to use it with T-Mobile is to buy a Gevey SIM. Even then, it only works with iOS 4. If you kept the phone current and upgraded it to iOS 5, unlocking is NOT POSSIBLE.

Either way, you sold a locked iPhone and buyer deserves a refund.

[Simon]

^Pretty much what he said. What firmware was it on when you sold it?