received confirmation from AT&T that my iphone is eligeble eligible to be unlocked from AT&T. I updated my IOS to 5.1 and restored all date from backup. But the phone is not working with no At&T SIM. - no sygnal, no activation in itunes
Contact AT&T.
Just because the device is elligible does not mean it is unlocked.
Nothing in your posting indicates you actually contacted AT&T and requested it be unlocked.
You need to have received the confirmation email from AT&T. The unlock must be done on the latest version of iOS, so if your phone is not currently on iOS 6 you must update first, then after updating, click the Restore button on the iPhone Summary screen in iTunes. This will reinstall iOS 6 and send an Activation request to Apple's servers; the response to the Activation request will be a message displayed in iTunes that says "Congratulations! Your iPhone is unlocked".
AT&T officcial unlock
