How to know if an iPhone is unlocked
I'm selling an iPhone. It's been reset. Sellers are asking me if it is unlocked. How do I know?
Windows, Windows 6
Question marked as
Settings->General->About->Carrier Lock. If it says no restrictions then it's not locked. Make sure you followed these instructions before selling it...
What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support