When we think about Amazon the first thing that comes to mind is usually its massive online store or maybe its line of Kindle tablets and e-readers, but the company also has its hands in plenty of other business you might not even know about. Now Amazon is expanding yet again with a new plan to serve as middleman for subscription-based online payments, potentially taking a huge chunk out of PayPal's revenue if it succeeds.

The new service, which launches next Monday according to Reuters, will leverage Amazon's roughly 240 million active users and their credit card numbers, allowing them to pay  recurring bills for their phones or music-streaming services directly through Amazon. The company then charges a fee for each transaction. This is a huge potential source of revenue for Amazon, which already makes 40 percent of its sales through similar middleman services.

Amazon's new venture could also help pave the way for its rumored smartphone, which it's expected to unveil at a press event set for June 18. The company's already tested its service with Canadian wireless service provider Ting, and could push the same subscription payments with its new device, though Amazon is also encouraging other companies to adopt the service as well.