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

https://www.bookmarking-keys.win/carrier-billing-lets-you-buy-apps-games-or-subscriptions-and-have-the-cost

Carrier billing lets you buy apps, games, or services and charge the cost directly to your mobile phone bill. If you have a monthly plan, the purchase adds to your regular bill. On pay-as-you-go plans, the amount is deducted from your available credit