AT&T is once again offering unlimited data for smartphone users, but there’s a pretty big catch. You have to be either a DirecTV or U-Verse subscriber in order to get it. That means you won’t be able to sign up for a new AT&T plan or upgrade your current plan to get unlimited data unless you’re also subscribed to DirecTV or U-Verse. If you do meet that requirement however, you’ll be able to sign up for the new plan fairly easily.
Pricing is $100 a month for a single line with an additional $40 added for each other line. For a limited time the fourth line on an unlimited account will be free of charge. That means you can have 4 lines with Unlimited data for just $180 (before taxes and fees). The carrier will also offer up to $500 in credit for those who switch from another carrier and trade in their device.Source: AT&T