Carrier billing lets you buy apps, games, or services and pay using your phone...

https://wiki-coast.win/index.php/Can_I_Use_Carrier_Billing_for_Parking_and_Transit_in_One_Month%3F

Carrier billing lets you buy apps, games, or services and pay using your phone bill. Instead of entering card details, your purchase is added to your monthly bill or taken from your prepaid credit