How do I unlock an iPhone for any carrier?

How do I unlock an iPhone for any carrier?

If you are still with carrier A, you have them give you the unlock code, after you have fulfilled your contract to pay for the phone and your plan in full.

Or you pay a cell phone unlocked service, to unlock the phone. Best to ALWAYS do this local to where you live and in person.

First you have an iPhone that can unlock to almost any carrier like 6s, SE, or 7 the ones that come in SIM-free