How can I get my iPhone unlocked to use with other carriers?

Hi there

1. Only your carrier can unlock your iPhone. Contact them and request an unlock. After you submit the request, it might take a few days to complete. Contact your carrier to check the status of your request.

See this Link for further reference

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

Only the original subsidizing / locking carrier can remove the lock.

If you are not a current, active subscriber of THAT carrier, they have virtually zero incentive to do so.

If you ARE their subscriber, they might help.

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

If you purchased a used phone, you will need to contact the seller to find out which carrier the phone is locked to. Then, you need to contact the carrier to ask them to remove the lock on the phone.