Previously, Verizon offered up to $300 back.
How to claim this offer: New and existing Verizon customers can get up to $300 for their old phone. And if you're switching to Verizon, there's an extra $100 in it for you.
For the $300: New Verizon customers will receive a VZW electronic gift card (which can be applied towards your bill) within 2 weeks and existing Verizon customers will receive an account credit in 1-2 billing cycles.
Note: You must buy a new smartphone with monthly device payments.
Fine print: New device payment activation & port-in req'd. $400=$300 trade-in VZW gift card + $100 bill credit. Bill credit applied w/in 2-3 billing cycles. Trade-in must be in good working condition.