Carrier billing lets you buy apps, games, or digital content using your mobile...

https://sergionyxy407.tearosediner.net/why-did-my-carrier-billing-payment-get-declined

Carrier billing lets you buy apps, games, or digital content using your mobile phone. Instead of a credit card, the cost is added to your monthly phone bill or taken from your pay-as-you-go balance. It’s a simple way to pay without entering card details.