The change could crimp the style of carriers like T-Mobile, which have pushed “bring your own device” as an incentive for switching service providers. Such carriers promise savings in exchange for using your existing phone on their network.
T-Mobile has promoted this notion for iPhones, in particular, since the company is the only one of the big four U.S. carriers that doesn’t sell the iPhone. The carrier goes so far as to feature ads displaying an open padlock, with an iPhone replacing the body of the lock. T-Mobile declined to comment.
Article Appeared @http://mashable.com/2013/01/23/unlocking-cellphones-illegal/