Go to Settings
Tap General
Tap About
Find Carrier Lock or Network Provider Lock
If it says No SIM restrictions, your iPhone is unlocked
If it shows a carrier or SIM restriction, your iPhone is locked
Insert a SIM card from another carrier
If the iPhone works and gets service, it is unlocked
If you see an error or no service, it may be locked
Contact your carrier and ask them to confirm the unlock status
Check the original purchase details if you bought it used
Use Apple’s coverage or device info only as a reference, not a direct unlock check