Carrier billing lets you buy apps, games, or services and charge the cost...

https://www.cool-bookmarks.win/carrier-billing-lets-you-pay-for-apps-music-or-other-digital-purchases-using

Carrier billing lets you buy apps, games, or services and charge the cost directly to your monthly phone bill or subtract it from your pay-as-you-go balance. It’s a simple way to pay without needing a credit card or bank account