If you haven’t tried my above suggestion to do a reset and clean install and then restore...
and you have also done a simple reboot of the phone...
you could also try seeing if you can update your carrier settings manually.
To manually check for and install a carrier settings update:
Make sure that your device is connected to a Wi-Fi network.
Tap Settings > General > About. If an update is available, you'll see an option to update your carrier settings.
To see the version of carrier settings on your device, tap Settings > General > About and look next to Carrier.