Carrier billing lets you pay for apps, games, or digital content by adding the...

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

Carrier billing lets you pay for apps, games, or digital content by adding the cost to your monthly phone bill or subtracting it from your prepaid balance. It’s a simple way to make purchases without needing a credit card or separate payment app