It seems that something is wrong with my iPhone

Good Afternoon!

If you get an alert that says Invalid SIM or No SIM Card installed, follow these steps.

1. Make sure that you have an active plan with your wireless carrier. 
2. Restart your iPhone or iPad.
3. Check for a carrier settings update. Go to Settings > General > About. If an update is available, you'll see a prompt to select OK or Update.
4. If your device has an eSIM, contact your carrier.
5. If your device has a physical SIM card, remove your iPhone SIM card or iPad SIM card from the SIM card tray and then put the SIM card back. Make sure that the SIM tray closes completely and isn’t loose. If you use a SIM tray from a different model iPhone, iPad, or from another phone manufacturer, it might not fit properly.
6. If your device has a physical SIM card and you've completed the previous step, try using another SIM card. If you don't have one, go to your carrier's retail store and ask them to test with another SIM card. You might need to replace your SIM card.

If you still see an alert about your SIM card, contact Apple support.

Regards,

Bryce

The phone has lost its connection to your carrier.

Contact your carrier to get things working again.