Phone promotions in the United States are usually built around trade-in value rather than a lower purchase price. The structure of that credit determines what the deal actually costs.
The credit is spread, not paid
Carrier trade-in offers commonly apply the value as a monthly bill credit across a two- or three-year installment plan rather than as money at the point of sale.
The customer still owes the full device price in installments, and the credit cancels those payments month by month as long as the account stays active.
Leaving early stops the credits while leaving the remaining device balance in place, which is the mechanism that makes the offer a retention tool.
Condition grading decides the offer that survives
The quoted value assumes a device that powers on, has an undamaged screen and is not carrier-locked or reported lost. Grading happens after the phone is received.
A downgrade at inspection reduces the credit rather than reversing the purchase, so the customer discovers the change on a later bill.
Photographing the device before shipping and keeping the tracking record is the practical defense, since the dispute is about condition at handover.
Plan requirements are part of the price
The largest trade-in values are usually tied to a specific service tier, and downgrading the plan can reduce or end the credits.
That effectively converts part of the phone discount into a commitment to a higher monthly rate for the length of the agreement.
Comparing offers therefore means comparing total service cost over the full term, not the trade-in figure alone.
Independent buyback works differently
Third-party buyback services and manufacturer programs generally pay cash or store credit at the time of the transaction, with no service obligation attached.
The headline number is usually lower than a carrier's maximum promotional value, because there is no multi-year contract subsidizing it.
The comparison is between a smaller amount with no strings and a larger amount conditional on staying put, which is a question about how settled the household is.
Why old devices still command value
A traded-in phone is refurbished and resold, used for parts, or exported to markets where older models remain in demand, so it retains recoverable worth.
Devices still receiving software updates are worth substantially more, because a supported phone can be resold as a functioning product rather than as components.
That support window, more than cosmetic condition, is what causes trade-in values to fall sharply at a particular point in a model's life.