Carrier billing lets you buy things online and pay through your phone account....

https://www.tumblr.com/magnificentlyultimatemist/827215471692627968/can-i-buy-transport-tickets-with-pay-by-phone

Carrier billing lets you buy things online and pay through your phone account. Instead of using a credit card, the cost appears on your monthly phone bill or comes out of your pay-as-you-go balance