Hanging on to that 5-year-old iPhone is about to pay off. Redbox sister companies ecoATM and Gazelle help consumers sell their used electronic devices with ease, turning that outdated smartphone or forgotten MP3 player into a paycheck and helping the planet in the process.

Owned by Outerwall Inc., the kiosk operator behind Redbox and Coinstar, the services offer two ways to part with abandoned devices.

As the name suggests, ecoATM is all about keeping it green, finding new homes for devices with life left in them and recycling the rest. The machines dot malls and retailers across the country, with several dozen locations in the Atlanta area. Located in places like Kroger and Wal-Mart, the bright green kiosks typically have users on their way in five minutes or fewer, cash in hand, ecoATM says.

The kiosks accept any cellphone, MP3 player or tablet, regardless of age or condition. To use, consumers insert their ID to prove they are at least 18 and then place their device in the kiosk for testing. After scanning the device, the machine tracks down the best price available and offers the owner the deal, ready to dispense cash on the spot.

Pricing varies based on the device model, condition and resale value. For example, a Galaxy S6 can fetch up to $115 while an iPhone 6s is worth up to $300, according to estimates on ecoATM's website.

For electronics that are beyond repair or too old to resell, ecoATM collects them for recycling, making sure the devices are disposed of responsibly to prevent the release of toxic chemicals. While the company does not buy chargers or other accessories, the kiosks will accept them for recycling.

Gazelle is a little pickier, buying iPhones, phones, tablets and iPods. Unlike ecoATM, it also takes used Apple computers, TVs or displays and sells certified used electronics.

The company tends to pay more than ecoATM for devices, currently offering up to $230 for a Galaxy S6 and $360 for an iPhone 6s, according to Gazelle.com quotes. However, it requires a little patience. Since the service is run through a website, sellers ship their device to the company for inspection and are mailed a check or gift card once everything checks out.

The selling process itself is pretty painless, with the website asking a few questions about the device and its condition before spitting out a price quote. Gazelle promises to lock in the price for 30 days, giving consumers the chance to replace their old standby and move their data over.

Once a seller is ready to say goodbye, they ship their device to Gazelle's warehouse on the company's dime. If the device matches the consumer's description, their compensation is sent on its way, often the same day the device gets to the warehouse, the company says. And if the device turns out to be in better shape than the seller thought, Gazelle will adjust the payout accordingly.

So, the next time you stumble across that box of long-ignored electronics gathering dust, don't set it aside for the next yard sale. With ecoATM and Gazelle, cash might be only a drive or click away.