Posted by: maxpayne August 4, 2010
using iPhone w/o data plan from ATT
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if your contract is over just swich to different carrier. Go to jaiklbreakme.com from your safari browser and then unlock it. its the easiest jailbreak and after that use 
http://www.engadget.com/2010/08/04/iphone-4-unlock-is-now-available/ to carrier unlock the phone.
full instructions and video at the link.
here is a youtube video of how its done 
http://www.youtube.com/watch?v=_5cvPyVGzgU&feature=player_embedded#!
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