How to use this Iphone 5 with a bad IMEI on straighttalk?

Someone sold me a bad IMEI AT&T iphone 5. I had an AT&T iphone 4 with straight talk prior to buying this phone. I didn't know the IMEI was bad so I bought the iphone 5 hoping to switch. I cut my SIM card and put it into the iphone 5. Everything worked perfectly fine so I went ahead and gave the dude the money. I went to sleep and wake up the next day and try to make a call and I get a message saying my phone has been blocked from the network. I contacted straight talk and they thought it was a problem of theirs so somehow they got my phone to work again. Everything was good, calls, texts, and data. 2 hours later, the same problem happens. So I call straight talk again, tell them the problem. They fix It again, 2 hours later, THE SAME PROBLEM. I gave up this time and began looking for answers. Is there any way I can use this iphone 5 with straight talk? There was a comment I saw through my search for answers where if I get another straight talk sim everything would work again.

It has a "bad IMEI" because it was reported stolen, lost or not paid for. The IMEI is blocked by the carrier. Get your money back from the person who "sold" it to you. It sounds like it was not theirs to sell… The IMEI is associated with the phone - not the SIM.