What is unlocking?
Phones are generally sold by wireless carriers for much less than their actual retail value. The wireless carriers often subsidizes the cost of the phone with the expectation that they can recover more than this amount throughout the subscriber's contract. They will try to make sure that the phone can only be used on their particular network, therefore locks the phone's software to their wireless network. Unlocking means clearing the phone's software setting so that the phone can be used on any GSM network. After your phone is unlocked, you can use it with any GSM service provider. (*frequency band may vary on makes and models)