How to change the IMEI number on iphone 4?

How can I change the IMEI number on my iphone 4s? Detailed instructions please!

You can't change the IMEI of the iPhone. It might be possible for other phones especially older models but these smartphones are difficult.

You can't. It's embedded into the phones firmware. Sorry but you can't reprogram stolen phones

EDIT:

Ahh. Well either way if the IMEI has been blacklisted then your phone just turned into a ipod since it will useless trying to get it on any carrier. You can still use it for web surfing and apps so long as you have Wi-Fi.

You'll have buy an online imei cleaner that's 50/50 in working. Best luck.

Actually my phone is not stolen. This phone is in my now ex boyfriends name and he reported it lost/stolen because he is mad I got a new boyfriend and I want my [phone back to working.

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Not possible. If what is happening is what you said, then go to your carrier & explain the situation to see what they could do to help.