Pay-by-phone lets you buy online and have the cost added right to your monthly...

https://rapid-wiki.win/index.php/Can_I_Use_Carrier_Billing_With_Prepaid_Credit%3F

Pay-by-phone lets you buy online and have the cost added right to your monthly phone bill or deducted from your prepaid credit. It’s a simple way to pay without needing a credit card or bank details