trade in phone

It all depends.

If you purchase the iPhone through the Apple online store in the U.S., here is the sequence.

• You pay the full price for the new iPhone
• The third party accepting trade-ins on Apple's behalf sends you packaging material
• You receive the material and send in the traded iPhone
• The third party inspects the iPhone and determines it matches (or does not match) the condition you specified
• If the condition matches, a credit is issued to the payment method you used to purchase the new iPhone

If you buy it an Apple Store it works a little differently, the store employee evaluates your iPhone, they apply that amount to your purchase and you don't have to send it in.