How to unlock SIM card on my iPhone?
How to activate or unlocked sim
[Re-Titled by Moderator]
iPhone 7, iOS 15
Question marked as
If you mean the SIM card is locked, you need to get the PUK code for it from your carrier.
If you mean your phone is locked to a carrier, you must contact the carrier it is locked to and ask about their unlocking policy→How to unlock your iPhone for use with a different carrier - Apple Support