My iPhone does not recognize the SIM card

Depending on the exact message you’re seeing, it might indicate that perhaps your phone is locked to a carrier OTHER that the carrier of the SIM you’ve installed.

Only the “locking carrier” can release the lock.

How to unlock your iPhone for use with a different carrier - Apple Support

If you see 'invalid SIM' or 'no SIM' on your iPhone or iPad.

If you see 'invalid SIM' or 'no SIM' on your iPhone or iPad - Apple Support