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

https://www.unitedbookmarkings.win/carrier-billing-lets-you-buy-things-like-apps-or-subscriptions-and-charge-the

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