My iPhone is unlocked, on China Mobile. I have well over 1200 contacts synching to the phone (from Address Book on the Mac) - most phone numbers are in "international" format - ie a plus sign, country code, then number, such as +4499999999.
I find when I make calls (from the contact list) or send/receive text messages, the contact name shows up correctly.
However, when I receive an incoming call - I only get the phone number on the display, not the caller's name, when they are definitely in my contact book.
Has anyone else found this problem? Is it due to the large number of contacts I have in my contact book, perhaps?