AT&T's official GoPhone prepaid policy has always officially prevented network data access for iPhones (and other 4G devices except for BlackBerry), but a tipster reports that will change tomorrow. The new policy adds 4G HSPA+ and LTE support as well as Visual Voicemail access to the GoPhone package, with customers able to bring their own device or buy a new one at off-contract unsubsidized prices. According to the details, existing customers with iPhones will be automatically updated with network access on June 21st, however they'll be able to call in and make the switch manually before that. The new features work on the $65, $50 and $25 monthly plans, however the two lower priced options will require data packages to work. You can get a peek at the leaked terms after the break, although we'd wait for an official announcement before picking up your 4G-capable handset and requesting service.