UVerse Internet IP address is wrong and needs to be fixed. How do I make it happen?

I'm asking this on the behalf of my father, who has had AT&T Internet for years and recently expanded to UVerse. He lives in the Florida panhandle, but his IP address shows his location as Mobile, AL (about an hour and a half west).

Here's the problem with this seemingly insignificant scenario: he subscribes to MLB.tv, the all-access internet-based Major League Baseball service that allows users to stream all live games during the season. However, this service still falls under all MLB Blackout rules. According to their web site, his zip code should have access to all games except for the Florida Marlins and Tampa Rays. However, he is able to watch these games so far this season, but is blacked out for Atlanta Braves games, which is the team he likes to watch. According to the MLB web site, the Atlanta Braves are blacked out in the Mobile, AL market, and they use IP address to determine which games to black out in your service. So their service thinks he is accessing from Mobile and therefore not allowed access to the games he wants, when in reality he is in Florida and should be granted access to them.

How can he fix his IP address so that it correctly shows his location and allows him to watch the games he should have access to? Thanks for any help anyone can provide.