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

https://wiki-aero.win/index.php/Does_Carrier_Billing_Work_for_Streaming_Subscriptions%3F

Carrier billing lets you buy apps, music, or subscriptions and have the cost added directly to your phone bill. If you use a pay-as-you-go plan, the purchase amount is taken from your available credit instead