Update required for mobile data on iPhone

You can check for a carrier update in Settings > General > About. Make sure your iPhone is connected to Wi-Fi to do so.

Manually update your carrier settings on your iPhone or iPad - Apple Support

"Update required for mobile data on iPhone: An update is required to use mobile data on this iPhone."

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Troubleshooting "No Service":

"No Service" is shown on the top-left corner of your screen. So, go here to fix that: If you See No Service or Searching on your iPhone or iPad - Apple Support. Give your Carrier a call, if no success.

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