Whether you already have an AT&T account, or you're choosing AT&T for the first time, it's easy to receive a $100 bill credit:
Purchase a new smartphone on AT&T Next.
Activate a new qualified wireless line of service on your new smartphone.
Remain active and in good standing.
Receive your $100 bill credit within 3 bill cycles
AT&T's Next upgrade program allows customers to purchase a smartphone or tablet with no money down and no contract, making monthly payments towards the retail cost of the device instead. Next also allows AT&T customers to upgrade their smartphone or tablet every 12 to 18 months after trading in their old devices.
AT&T offers both 20 and 24-month Next installment plans, which equate to a $32.50 or $27.09 monthly payment for an iPhone 5s, in addition to plan fees.
The Next promotion will end on 9/30/14, which means it will likely still be valid when Apple releases the iPhone 6. It is, however, limited to new lines and not available for upgrades.