I have an American Standard ZTE Open w/ FFOS 1.1 update. I am from the U.S. and incoming calls would not be matched with existing contact list entry unless it's stored in this format: 1-(3 digit areacode)-(7 digit phone number) like this: 12121112222. But in the U.S., I could call someone from the mobile phone with or without the "1" in front.

It's common practice for mobile phones to be able to pick up the caller id for an incoming call even it's stored without the 1 in front. This has been the case for all the phone I've had for the past 10 years across different make and models.