Phones that take a Sim card are generally GSM phones. Most of the time the phone is locked to use only a sim card and service from a specific provider like at&t and T-mobile. When you have your phone unlocked you can use any sim card and any Service. So you can use your Iphone with T-Mobile or who ever you want.

We are able to unlock almost any GSM phone including the Iphone. Usually same day!!