Carrier billing lets you buy apps, games, or services and pay for them through...

https://www.play-bookmarks.win/carrier-billing-lets-you-buy-apps-games-or-media-by-adding-the-cost-to-your

Carrier billing lets you buy apps, games, or services and pay for them through your mobile phone account. Instead of using a credit card, the cost is added to your monthly phone bill or taken from your prepaid balance