Carrier billing lets you buy apps, games, or services and charge the cost...

https://articlegrovey.com/s/gE_cs41ApV77nwDee3Qp6

Carrier billing lets you buy apps, games, or services and charge the cost directly to your phone bill. If you have a monthly plan, the purchase shows up on your next statement. For pay-as-you-go users, the amount is taken from your prepaid credit balance