Is this the Verizon model? Are you thinking Verizon's prepaid plans?
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
Currently it is not possible to use an iPhone on a VZW prepaid. While other prepaid carriers have this option, VZW has yet to deliver a prepaid option for the more modern devices. Even the android prepaid phones that are offered, are dated with respect to current models.