How to use carrier billing?

See here: Availability of mobile phone billing as an Apple ID payment method - Apple Support

Make sure you are in a country where the option is supported by Apple. Just because the carrier supports it, does notmean Apple supports it for your country.

Contact your carrier and see if it's an option they offer. If it is, they should be able to provide you with instructions. It's not something that all carriers offer.

Then Apple does not support Carrier billing there.