Carrier billing lets you buy things online or in apps and pay for them through...

https://www.bookmarkidea.win/carrier-billing-lets-you-pay-for-apps-games-or-digital-content-by-adding-the

Carrier billing lets you buy things online or in apps and pay for them through your mobile phone account. The amount shows up on your monthly phone bill or is taken from your prepaid credit if you use pay-as-you-go service