The adoption of carrier billing got another boost today when Microsoft announced it had partnered with Sprint and San Francisco-based Boku to enable U.S. customers to make purchases from the Windows Store.

While Windows phones are still struggling to gain traction, it’s notable that customers will be able to use carrier billing to make purchases from the desktop as well as mobile versions of Windows 10.

“What we’re seeing, through a variety of announcements, is in effect the emergence of a new global payment system,” said Jon Prideaux, chief executive of Boku. “If you want to sell more stuff, you move beyond credit cards and move on to carrier billing.”

Starting today, Windows 10 users who are Sprint customers can add their phone number to the Windows Store and make purchases on any gadget. Boku says it is the first carrier billing provider for Windows 10 and so far, Microsoft’s only U.S. carrier billing partner.

As the name suggests, carrier billing lets users make purchases through their devices without needing to enter a credit card for each separate transaction or service. The amount is simply applied to their monthly carrier bill.

Initially, carrier billing was seen as an attractive service for consumers in emerging economies where credit cards have smaller penetration rates. However, in recent weeks, the service has begun to move to developed economies as well. Apple recently began offering carrier billing for its German App Store, which sources say is powered by Boku, though the company won’t confirm that.

The reason carrier building is expanding is simple: Boku says its data shows that purchases of apps and content like music and movies increases wherever carrier billing is available.

Boku, with about 155 employees, has raised about $75 million in venture capital from Andreessen Horowitz, Khosla Ventures, and Benchmark. The firm has also snagged deals with several gaming companies and Facebook.

Another major competitor in this field, Bango, is based in the U.K. and has landed partnerships to provide carrier billing for the app stores for Google, Amazon, Samsung, BlackBerry, and Firefox.

To some extent, the biggies are still dipping their toes into the water. It will be interesting to see in 2016 whether Apple brings the service to places like the U.S. and China, and whether Microsoft brings aboard more carriers like AT&T and Verizon Wireless.