Carrier billing lets you buy apps, games, or services and charge them straight...

https://aged-wiki.win/index.php/Is_Carrier_Billing_the_Same_as_Paying_by_Text%3F

Carrier billing lets you buy apps, games, or services and charge them straight to your phone bill. Whether you have a monthly plan or use pay-as-you-go credit, the cost is added to your next phone bill or deducted from your available balance