Unlock SIM with PIN and PUK

See this Apple article: Use a SIM PIN for your iPhone or iPad

Use a SIM PIN for your iPhone or iPad - Apple Support

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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 your iPhone SIM card or iPad SIM card and check the card for the carrier's name or logo.
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4. Ask your carrier to help you unlock your SIM card using the default SIM PIN or PUK code. 
5. 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.

SIM PINS and PUKs are carrier functions. You'll need to contact them.

bugguts83 wrote:

Yeah but the thing is, this behavior is different than it was on iPhone X, I know the code and am entering it correctly and it keeps prompting me to change the PIN afterward, which fails.

That's as may be. Your carrier is still the only one who can fix this.

Have you forgotten your password? -> See this Apple article: If you forgot your Apple ID password

If you forgot your Apple ID password - Apple Support

Then see this Apple article: What to do after you change your Apple ID or password

What to do after you change your Apple ID or password - Apple Support

See this Apple article: Use a SIM PIN for your iPhone or iPad

Use a SIM PIN for your iPhone or iPad - Apple Support

How to reset your iPhone, iPad or iPod touch if you've forgotten your passcode

How to reset your iPhone, iPad or iPod touch if you've forgotten your passcode – Apple Support (UK)

I don’t no my puk code and now i cant call people or use mobil data

Contact your carrier for help with this.