I can’t use my SIM card

It appears that your iPhone is locked to a particular carrier and you are attempting to use your iPhone on a different carrier. Carrier locked iPhone can only be unlocked by the carrier that the iPhone is locked to. Call the carrier with whom the iPhone as initially working with and ask them to unlock the iPhone. There are requirements that need to be met, and are specific to each carrier, before they will perform the unlock.

If you have bough a previously owned iPhone then you will need to get it touch with the seller and see if s/he is willing to help in calling the initial carrier. Good Luck.

Axel F.

Where did you buy the phone?

What carrier are you trying to use?

~Lyssa