Carrier billing lets you buy apps, games, or media by adding the cost to your...

https://dibz.me/blog/why-do-carriers-cap-carrier-billing-daily-or-monthly-1245

Carrier billing lets you buy apps, games, or media by adding the cost to your phone bill or deducting it from your pay-as-you-go balance. It’s a simple way to pay without needing a credit card or separate account