You can go ahead and consider Aio Wireless an option the next time you're shopping among mobile carriers, because the prepaid subsidiary of AT&T is now available nationwide. Service plans at Aio feature unlimited voice, messaging and overage-free data, and start at $40 per month for simple phones. Smartphone users can expect to pay at least $55 at Aio, which fetches 2GB of high-speed data, whereas the $70 plan comes with a healthy 7GB allotment. As one potential gotcha, the carrier throttles its
