Can I Update to iOS8 with bad IMEI?

[ilikechicken123]

This might be a dumb question....
My friend gave me an iPhone 4s a year or two ago. It's an AT&T iPhone. He thought it was bricked as it was stuck on the connect to iTunes screen and whenever he connected it to itunes it says he needed to restore but it would always give him an error. He gave it to me and said I could mess with it. I never was able to fix it until recently. I've had it unlocked to metropcs and they checked my IMEI and they said it was clear and i could get it onto their carrier. So today, I ported my number over to cricket wireless and they checked my IMEI and said it was reported lost or stolen. But I know my friend didn't do that and I know I didn't. They were still able to get it onto their carrier, I'm not entirely sure how. But I checked for myself and it is indeed a bad IMEI. So I have three questions.
1. Is it possible to have the IMEI blacklisted through find my iphone? Because I've set it on lost mode a few times form there.
2. Is it possible that MetroPCS blacklisted my IMEI?
3. I'm on iOS 7, is it possible to update to iOS 8 without it making my phone useless? Like, will i still be able to pass through the activation part of the update even though I have a bad IMEI? I want to keep my service with Cricket, which is part of AT&T

I honestly have no idea how my IMEI got blacklisted......

 

[iOS Gravity]

I think that you will be able to use update to iOS 8 without any trouble seeing that the phone is already activated. If the IMEI hasn't been blacklisted until recently, it could've been Metro PCS that did that. I'm not sure why they would do that.