"NTT Docomo Inc. has decided to unlock its cell phones' subscriber identity modules (SIMs) for all handsets on sale from April 2011..Once the lock is removed, a user will be able to switch mobile phone service providers without having to buy a new handset"
Source:Docomo to unlock cell phones from April
Jul. 7, 2010
Daily Yomiuri
http://www.yomiuri.co.jp/dy/business/T100706004091.htm
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