I'm having an interesting problem as well.
I recently had verizon unlock my 4S sim slot for international use. After doing that, all incoming phone calls have "+1" in front of them. None of my contacts in the US have the country code, so my caller ID wasnt working for phone calls.
Now the funny part is - for text messaging, the "+1" doesnt show up. So after adding "+1" to all my contacts, now my messaging caller ID doesnt work 😡
Do I really need to have two versions of every contact's phone number now? Excuse my language, but that's a half a s s fix. Now anytime i want to use siri, i need to take an additional step to specify if im calling "work" or "mobile", even though they're the same number.