With AT&T NextSM, you can buy iPhone with $0 upfront and trade up to a new one every 12 or 18 months.
AT&T NextSM gives you the flexibility to choose a 12- or 18-month trade-in period and get the latest iPhone sooner than you would with a two-year contract. A 24-month trade-in option is also available at an Apple Retail Store. If you’re on (or switch to) an AT&T Mobile Share Value® plan, you can even save up to $25 per month* on your wireless service when you buy a new iPhone using AT&T NextSM.