If you have no contacts on your iPhone, the incoming call has no way matching the number of the incoming call with a name. Is the number appearing or does it say 'unknown' caller.
It also could be that the callers have their phones - whether mobile or land line - set to not sending a caller ID.
Thanks for the update. The problem with unlocked iPhones is that we have no way of knowing whether the problem you describe is a legit software problem, or one as a result of the unlocking process. I'd be tempted to reset alll network settings (Settings>General>Reset), to see if it helps. If not, I think you might be better off seeking help on another forum that supports unlocked iPhones, or at least knows more about the problems associated with them. Sorry not to be of more help to you.
we 3 weeks ago bought an iPhone in Austria (t-mobile network). The phone is not unlocked! We have the same problem, that the caller ID list shows only phone numbers and not the names of the person in our iPhone contact list. This happens despite the fact that the caller IDs are not put on hide on the caller's phones. We synchronized the contacts via my Power book to the iPhone.
I really have no idea why this is happening. Please help. Regards Christian
Your problem is slightly different from the OPs, as you are getting the phone numbers. What is probably happening is your contact list numbers do no match the incoming number because the country code is in one but not the other.
I had the same problem you might have to go back and edit you contacts information to and put the 1 before the number or not also try putting the plus ➕ sign in front of the number that seems to work for me. Its a headache since I have over 800 contacts.
I have the same type of phone you do (the unspoken type).