Carrier billing lets you pay for apps, games, or digital content by charging...

https://remingtonsgreatchat.wordcanopy.com/posts/what-is-the-best-way-to-track-carrier-billing-spending

Carrier billing lets you pay for apps, games, or digital content by charging the cost to your phone bill. If you have a monthly plan, the amount appears on your next bill. For pay-as-you-go users, the charge is taken from your available credit