A Yahoo Answers user asked if she could use her post-paid, contract Verizon iPhone 5 on a prepaid plan.
The good news is that a Verizon iPhone 5 can be activated on a prepaid plan, including on MVNOs. In fact, some MVNOs offering service on the Verizon network now offer LTE. At the time of writing, Page Plus offers LTE on plans from $30/month.
Users have also reported using the Verizon iPhone 5 on AT&T-based plans with great success. However, they note that LTE does not work on the AT&T network with the iPhone 5.
In either case, make sure you end your contract cleanly: either let the contract expire, or close your account and pay any termination fees. Phones that have been blacklisted for non-payment or being stolen will not be eligible for activation on any service. When you activate your phone with your new service, make sure to get the right size SIM card for your iPhone 5: a Nano-SIM.
Note this information is specific to the iPhone 5, not any other iPhone model.