I needed to an unlock SIM card

Are you trying to unlock a phone to use a different SIM, or are you trying to unlock a SIM card that is asking for a PIN? Those are two different things that have two different solutions.

If you are seeing an iPhone that will not activated because the SIM is not supported, then you need to have the phone unlocked by the carrier that has the lock on the phone. The carrier with the lock is the only one that can unlock it. Apple does not unlock phones.

If the SIM is locked and asking for a PIN and you do not know it, you need to contact your carrier and ask them for the PIN. That is a carrier function.