Apple Inc. has started an iPhone trade-in program letting owners sell older handsets back to the company in exchange for credit toward a new model.

Apple’s U.S. retail stores are now accepting devices, said Amy Bessette, a spokeswoman for Apple. The initiative is starting just before the next iPhone’s debut on Sept. 10.

The credit can be used toward the purchase of a new iPhone, which will be activated in the store.

It didn’t say how much older phones would be worth. But other brokers such as Gazelle.com offer anywhere from $10 for a working iPhone 3G to $350 for an iPhone 5 that is in pristine condition.

Similar trade-in programs are run by retailers including Best Buy, Target and Radio Shack.

The Apple trade-in program is the first program run by the iPhone maker. By buying old phones, they’re aiming to spur new device sales by helping cover the cost of buying the latest smartphone. Apple is teaming up with Brightstar Corp., a mobile-phone distributor, to run the operation, people with knowledge of the plans said in June.

“IPhones hold great value so Apple Retail Stores are launching a new program to assist customers who wish to bring in their previous-generation iPhone for reuse or recycling,” Bessette said. “In addition to helping support the environment, customers will be able to receive a credit for their returned phone that they can use toward the purchase of a new iPhone.”

The amount of credit awarded for the trade-in depends on the condition of the phone. An iPhone 5 with 64 gigabytes of memory can fetch $350 through Gazelle’s website, while an iPhone 3GS may receive only $10. The most that any iPhone will fetch at an Apple Store is $280.

Without a subsidy from a carrier, an iPhone 5 costs $649 to $849 depending on the amount of memory, compared with $199 to $399 with a wireless contract.

Used iPhones collected through these programs are often refurbished and used as replacements for ones that break, or resold in emerging markets.

(The Associated Press and Bloomberg News contributed to this report)