Your carrier can assist with unlocking the phone, provided it meets the requirements. Those requirements are typically that the phone was or is paid off and the line it was on is in good standing. Some will even give you the unlock code at no cost. You can search Google for the process, it's usually posted on the carrier sites.
That said, if it is a Verizon device, it is network-unlocked but it will still be restricted as to what networks it'll work on based on the radios that are installed in the device.
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