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

https://nova-wiki.win/index.php/What_Is_the_Simplest_Explanation_of_Carrier_Billing_for_a_Friend%3F

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