It's easy to see up to $1,000 off the price of something and get excited, but make sure you know what you're signing up for. AT&T's applies these discounts as bill credits that are usually spread out across a 36-month period. Sometimes, part of the discount amount is given in the form of a prepaid gift card (for a trade-in) and the rest is done as bill credits, but that's specified when it's happening.