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

https://www.first-bookmarkings.win/carrier-billing-lets-you-pay-for-apps-games-or-services-by-adding-the-cost-to

Carrier billing lets you buy apps, games, or services and charge the cost directly to your phone bill. If you have a monthly plan, the purchase appears on your next bill. For prepaid users, the amount is deducted from your available pay-as-you-go credit