It's probably SMS/phone call billing. You know those "No Credit Card? Pay By Phone" links on the biller page.
Laws vary a lot by country, in some of them the phone billers can only charge a dollar.
They use GXBill as I can see, which doesn't list its rates in the public. But here's a list from another biller, just so you can get an idea. Site income on phone billing joins should be similar to this.
Global Access: Alternative Payment Processing, SMS Billing