Carrier billing lets you buy apps, games, or digital content and charge the...

https://papa-wiki.win/index.php/Does_Carrier_Billing_Replace_Cards_or_Just_Sit_Alongside_Them%3F

Carrier billing lets you buy apps, games, or digital content and charge the cost to your monthly phone bill or take it from your pay-as-you-go credit. It’s a simple way to pay without using a credit card or entering payment details each time