AT&T is adding more data to its GoPhone prepaid smartphone plans without raising monthly fees in the process. If you're currently paying $60 a month for 2GB, your allotment will jump to 2.5 gigs, while those on the $40, 250MB plan will now get 500MB per month. More data is only part of the value proposition for GoPhone customers, though; the new 2.5GB plan will now offer the ability to use your phone as a WiFi hotspot.Additionally, the carrier is adding a new $45 plan that includes 1GB of data and unlimited talk -- but note that this is only available at Walmart. While these updates are good news for current GoPhone subscribers, they're not quite as competitive as T-Mobile's pay-in-advance plans, which start at $30 a month with unlimited (read: 5GB) data and 100 minutes of talk. That said, $60 a month for 2.5GB and hotspot functionality is a nice step up on AT&T's part.