It's called SIMLOCK removal and no, nothing wrong will happen.
#1534771 by unknown[81460] at 2013-06-28 19:19:58 (4 weeks ago) - [Report]
As they said no. I looked into unlocking my iphone for the wife as I will be getting an upgrade soon. She is on a different network. I pay £15 to my provider (three) and they unlock the phone to allow any sim. Then its free to use with any sim. In this instance as my wife has a blackberry I will probs call her provider (Orange) and change the dataplan to allow more data as hers doesnt have much data usage. Prices differ depending on what company the phone is locked into.
Allot of people give up their contracts and get pre paid monthly sims and they work fine.