Pay-by-phone lets you buy digital products or services by charging the cost...
https://weekly-wiki.win/index.php/What_Does_Frictionless_Checkout_Mean_in_E-Commerce%3F
Pay-by-phone lets you buy digital products or services by charging the cost directly to your monthly phone bill or prepaid credit. It’s a simple way to pay without entering card details, making checkout faster and easier on your mobile device