Carrier billing lets you buy apps, games, or digital content without a credit...

https://www.golf-bookmarks.win/carrier-billing-lets-you-buy-apps-games-or-subscriptions-and-charge-the-cost-1

Carrier billing lets you buy apps, games, or digital content without a credit card. Instead, the cost is added to your monthly phone bill or taken from your prepaid balance if you use pay-as-you-go