Blocked iPhone 4S by IMEI.. ?

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here's the issue. A friend of mine, living in France lost his iPhone 4S . Luckily, he got an insurance, and they gave him a new one after a week. Turns out, 2 weeks later, a friend of him found the phone at his home (apparently my friend forgot it at an afterparty there, somewhere between the couch parts! ) , so that particular guy gave it back to my friend.

Anyway, as reported for being lost (or stolen, dunno exactly what he told the insurance company), they called the appropriate people and blocked the phone by IMEI. So, basically, it is unusable now.

- So, question is : is there a way of unblocking such a phone ? (would a normal jailbreak work? ) I'm not sure if there are jailbreaks for iOS 6.

- if not, I've heard that IMEI blocked phones don't work with local SIM-cards, but for example, I live in Belgium and it could work with a Belgian card ? Or is this bs ?

i'm asking, coz i have an iPhone 4, and my friend is proposing me this iphone 4s at a very good price..

thanks for your feedback!