Cofounder here. All service is prepaid, and we have a credit transfer system built-in. The network operator can load up credits onto someone's account directly through our management interface, and that user can resell it to whoever they like. For example, a network operator could sell credits in bulk directly to shop owners, who could then resell to the community at large.

This is only for data, no voice, right? Otherwise how would you negotiate with the other carriers/federal body to generate/register valid phone numbers?

BTW how do you handle roaming? Does the SIM card only work for your particular carrier? Or does it somehow integrate with the existing ones?