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

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

Carrier billing lets you buy apps, games, or digital content and have the cost added directly to your monthly phone bill or taken from your pay-as-you-go balance. It’s a simple way to make payments without credit cards or separate accounts