Carrier billing lets you buy apps, games, or subscriptions and have the cost...

https://bizzmarkblog.com/carrier-billing-for-subscriptions-is-it-easy-to-cancel/

Carrier billing lets you buy apps, games, or subscriptions and have the cost added to your monthly phone bill or taken from your prepaid credit. It’s a simple way to pay without entering card details, making small purchases easier on your phone.