Incoming calls all of a sudden display international format numbers

All of the sudden, beginning yesterday, incoming calls show as an international formatted phone number and thus are not showing the name(s) from my contact list. I'm in the US.
For instance, all local calls here in Arizona have a 520 prefix, so my friends phone numbers in my contact list would be 520-xxx-xxxx.
Since I've had the phone all incoming numbers from anyone in my contact list would show their name as the caller ID.
Not, starting yesterday, all of the sudden, a local incoming call shows as: +52 0xx xxxx x
Any idea why ?

Thanks,
Fred