What do you mean "hard reset"? You do not need to to this to complete the unlock. How was the simlock removed by ATT? Did you get a confirmation message from ATT saying that your phone was indeed unlocked? Did you follow the instructions on the email and restore the phone via iTunes?
I got confirmation email by AT&T and also checked that the phone is now registered as unlocked.
with hard reset I mean that I erased all data en programs by hloding front button and top on/off button at the same time for a while.
When phone starts again you have to fill in language and country and then the phone makes contact with iTunes, but doesn't succeed to reach the activation server
Again, did you connect to iTunes and do the restore with the ATT SIM in the phone? Erasing is not enough. When you completed the restore, did you get a message saying :"Congratulations, your iPhone is now unlocked?"
Was your phone ever hacked/jailbroken in the past?
I connected to Itunes, but with a Dutch active SIM card. But I-Tunes did not activated the Phone at all. It was just like " I don't know you and do nothing.
But you are on the spot that the phone had been jailbroken in the past, although it now if registerd unlocked by AT&T at my request.
1). You will need the ATT SIM to complete the unlock process.
2). Since your phone was jailbroken/hacked in the past, that is probably the reason why your cannot complete the legitimate unlock.
3). Since your phone was jailbroken/hacked, you cannot get any futher help here as we cannot help you as per forum terms of usage. You will need to find help elesewhere.
Sorry and good luck.