There is no public database of blacklisted iPhones. If you are in doubt,
return the iPhone and get your money back. Even if you could prove the
iPhone is not blacklisted today, there is no way to prevent if from becoming
blacklisted in the future.
Common scam is to sell iPhone and then report as lost/stolen for insurance.
iPhone becomes blacklisted and buyer now has inoperative iPhone that cannot
When you buy from an unreliable source, you take your chances. To my knowledge, for those networks that actually do utilize IMEI blocking of devices on their network (no USA network currently does), once a device ID is in the blocked database, it is permanently so and will not be removed, so knowing it is blocked now is unlikely to help you at all if it is.