Probably due to the formatting of your contacts phone numbers.
For example, you got someone entered as 1555555555, but when they call, the caller ID is 555555555, hence it may skip out on it.
Also try remove the ()- formatting. You can't write it on the phone, but when I sync with outlook, they get passed on ( +1 (555)555-555 )
However, I havent tested if I get the names to show up. Im too lazy to try now, I got no other phone to call myself with