Time for an upgrade, AT&T users! Beginning May 1, you'll be able to trade in your current smartphone

Time for an upgrade, AT&T users! Beginning May 1, you'll be able to trade in your current smartphone for at least $100 off a new one (as long as you re-up for another 2 year contract). That means you can get an iPhone or a Galaxy S4 for a bill less than usual, even if the smartphone you're trading in is an old crappy one.