Hello gabriellefromcv,
Let's start off by checking the helpful steps in this article which can help with this issue: If you can't make or receive calls on your iPhone - Apple Support. Follow any steps here you've not already taken:
"Contact your carrier
When you contact your carrier, make sure that:
- Your account is set up to use your iPhone.
- There aren't any localized service outages.
- Your account doesn't have a billing-related block.
- Your calls don't have errors on the carrier system.
Update your software
- Check for a carrier settings update.
- Check for an iOS software update. Some updates might require a Wi-Fi connection.
Check your iPhone settings
- Turn Airplane Mode on and off. Go to Settings and turn on Airplane Mode, wait five seconds, then turn it off.
- Check Do Not Disturb. Go to Settings > Focus > Do Not Disturb and make sure it's off.
- Check for any blocked phone numbers. Go to Settings > Phone > Blocked Contacts.
- See if Call Forwarding is turned on. Go to Settings > Phone > Call Forwarding and make sure it's off.
- Check to see if Silence Unknown Callers is turned on. If the setting is on, a caller must be listed in your Contacts or Recents. Or they must have shared their number in Mail or sent you a message using that number in order for their call to go through. Add their number to Contacts to ensure the phone rings. Calls from some third-party apps might not go through.
Check your network settings
- Reset your network settings. Go to Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings. This will erase all current saved settings, including Wi-Fi passwords, preferred networks, and VPN settings.
- Try to make or receive calls in another location.
Contact Apple Support
If you still can't make or receive calls, contact Apple Support, then follow the steps to complete your request."
Let us know if we can help with anything else at all or if this doesn't settle your issue so we can look into this further with you. Thanks and have a fabulous day!