Carrier billing lets you buy things using your phone without a credit card or...

https://harpersnewinsight.brightsora.com/posts/why-does-carrier-billing-show-up-as-a-weird-line-item-on-your-bill

Carrier billing lets you buy things using your phone without a credit card or app store account. Instead, purchases are added to your monthly phone bill or taken from your pay-as-you-go balance