To date, Straight Talk's LTE support has been limited to a warmed-over Sprint version of the Galaxy S III. Now there's a much better option: the prepaid carrier has started selling SIM cards that support unlocked devices with AT&T-compatible LTE. The upgrade potentially offers a better bargain than AT&T's own Aio Wireless, giving customers unlimited LTE data, voice and text for $45 per month versus Aio's $55. It's not quite paradise, however. Straight Talk is known to throttle data, which could prove all the more frustrating at 4G speeds.