Carrier billing lets you pay for apps, games, or subscriptions by charging the...

https://www.joint-bookmarks.win/carrier-billing-lets-you-pay-for-digital-purchases-by-adding-the-cost-to-your

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