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Why unlock?
When you buy a new phone, chances are it'll be locked to the network you bought it on, and if you try to put another network's Sim card in it simply won't function.
Unlocking your mobile enables the phone to be used with any compatible Sim card on any network.
Why do mobile phone companies lock phones?
Mobile companies say their phones are already heavily subsidised to entice you to buy them and they need to make up this shortfall. Yet the reality, as ever, comes down to cold hard cash; it makes no sense to sell you the phone at reduced cost and then let you take your money to another network provider.
Isn't it illegal?
Nope, this is a common misconception, and one the mobile phone companies (unsurprisingly) aren't keen to dispel. The confusion arises because unlocking and unblocking are often mixed up, yet mean different things.
Unlocking is totally legal. It just means making the phone work with any Sim card.
Unblocking is illegal. This is the practice of making a phone work again after it's been blocked by the networks, usually as a result of its being reported lost or stolen. Unsurprisingly, It is thoroughly illegal and should not be attempted.
Source :
http://rapid*share.com/files/160240323/unlockcellphone_vietproblog.com.rar
