Carrier billing lets you buy apps, games, or subscriptions and charge them to...

https://www.bookmarking-keys.win/carrier-billing-lets-you-pay-for-apps-games-or-services-by-charging-the-cost

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