Here’s how it works: Sales tax applies. You’ll need email & ID (to verify your name & address) to sign up. Stay on your Flex plan for 12 months and then trade-in your working phone to get the same great deals as new customers on select devices. You can do on this up to 4 lines (each line has its own countdown). The longer you wait, the more devices you can choose from. When you swap or if you cancel service, the countdown for your next deal restarts. Current Metro or T-Mobile customer? Just switch to a Flex plan and you’re ready for deals after 12 months. Heads up--if you get a discounted phone when you join or add-a-line and want to move to a less expensive rate plan during the next 6 months, you'll need to pay $50 to change plans. Like everything else in this crazy world, Metro Flex details could change.