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

https://wiki-spirit.win/index.php/Can_I_Use_Carrier_Billing_for_App_Store_Purchases%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