I'm betting that your IP address range being assigned by U-verse HSI for your area is not being properly identified as being within the United States by the service used by the entertainment.att.net site.  Visit www.ip2location.com (or some similar site) and see where it says you are.  I have no idea what service entertainment.att.net uses for this, so the results from this particular link aren't conclusive, but may be enlighening.