Carrier billing lets you pay for apps, games, or services by adding the cost to...

https://www.adirs-bookmarks.win/carrier-billing-lets-you-buy-digital-products-or-services-and-pay-using-your

Carrier billing lets you pay for apps, games, or services by adding the cost to your monthly phone bill or subtracting it from your prepaid credit. It’s a simple way to make purchases without entering card details