cannot unlock Sim

Turn your SIM PIN on or off

1. If you have an iPhone, go to Settings > Cellular > SIM PIN. If you have an iPad, go to Settings > Mobile Data > SIM PIN.
2. Turn on your SIM PIN or turn it off.
3. If asked, enter your SIM PIN. If you've never used one, enter the default SIM PIN from your carrier. If you don’t know the default SIM PIN, don't try to guess it. Check your carrier's customer service page or the documents that came with your wireless plan. Or you can contact your carrier.
4. Tap Done.

If you forgot or don't know your SIM PIN

Never try to guess a SIM PIN or PUK code.* The wrong guess can permanently lock your SIM card, and then you would need a new SIM card. If your device asks for a PIN or code that you don't know, here's what to do:

1. Contact the carrier that gave you the SIM card. If you aren't sure which carrier to call, remove the SIM card and check the card for the carrier's name or logo.
2. 
3. Ask your carrier to help you unlock your SIM card using the default SIM PIN or PUK code. 
4. If you can't unlock your SIM card using the SIM PIN or PUK code or if an alert says, "PUK exhausted," ask for a new SIM card.

*If you enter the wrong SIM PIN too many times, your wireless carrier might be able to give you a Personal Unlocking Key (PUK).