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

https://noon-wiki.win/index.php/Carrier_Billing_for_Parking:_What_Happens_If_I_Hit_My_Limit%3F

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 appears on your next bill. For pay-as-you-go users, the amount is taken from your available credit