No Service even if th SIM is correct

Check your coverage area

Make sure that you're in an area with cellular network coverage. Then follow these steps:

• To turn cellular data on or off, go to Settings, then tap Cellular or Mobile Data. If you're using your iPad, you might see Settings > Cellular Data.
• If you're traveling internationally, make sure that your device is set up for data roaming. Go to Settings > Cellular > Cellular Data Options > Data Roaming.
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Contact your carrier

Issues with your carrier or account might affect your service. Contact your carrier to:

• Verify that your account is active and in good standing.
• Make sure there are no outages in your area.
• Check that your device isn't blocked from receiving cellular services and is set up with the right data plan.

Only your wireless carrier can access and manage details about your account. If you need help finding your wireless carrier's service page, use the Apple carrier-support article or an online search engine.

If you see No Service or Searching on your iPhone or iPad - Apple ...

https://support.apple.com/en-us/HT201415