Apple is providing smartphone owners yet another way to buy an iPhone.

Starting today, and currently only available in Apple Stores, Apple's Trade Up With Installments program gives people the option of trading in their old iPhone and pay a monthly fee that's cheaper than the company's ongoing iPhone upgrade plan. According to USA Today, even older devices like the iPhone 4 are eligible for trade-in.

The new program works like this: You decide to upgrade from your iPhone 6 to the iPhone 6S, and the resulting monthly payment ends up being about $15 for 24 months. Or, if you're going from the aforementioned iPhone 4 to the 128 GB iPhone 6S Plus, you'll end up paying roughly $35/month. There aren't exact prices available for how the trade-up will work, but you'll basically be paying around $15 if you're going from one iPhone to the one that directly succeeded it.

Interestingly enough, Apple's new program is also open to Android and Windows phones. That said, if you don't want to trade in your current device for an iPhone, there's the option to ask for credit as well. Credit for iPhones varies by models and size, while Apple will offer up to $300 for Android and Windows devices.

In other iPhone related news, the Cupertino-based company is going against the FBI's wishes to create a backdoor for the iPhone, and it just recently released an update to undo the damage done by Error 53