Pay-by-phone transactions let you buy digital goods without entering card...

https://ariassplendidinsight.swiftnestly.com/posts/carrier-billing-vs-bank-transfer-for-digital-purchases

Pay-by-phone transactions let you buy digital goods without entering card details. Charges go straight to your monthly phone bill or use prepaid credit if you have it. It’s a simple way to pay that works well on mobile and keeps checkout fast and easy.