How can I check in Itunes if Iphone is unlocked without simcard
How can I check in Itunes if Iphone is unlocked without simcard, it is locked to AT&T and they confirmed they will unlock it... prevoiusly when I use to connect Itunes says something like this "Invalid sim" and it doesnt let me sync my phone which is not the case today, as it allows me to sync and let me show all details on the summary page and phone number is n/a
Is this unlocked ? can you advice
iPhone 4