How do I fix SOS on my iPhone X?

Leg53 wrote:

How can I make calls again?

See here:

If you see SOS, No Service, or Searching on your iPhone or iPad - Apple Support

If you see SOS or "SOS only" in the status bar, your device isn't connected to your cellular network, but you can still make emergency calls through other carrier networks. 

First step is to try to reconnect to your cellular network:

If your cellular network is available, you might be able to reconnect to it by following these steps:

1. Go to Settings.
2. Turn on Airplane Mode for at least 15 seconds.
3. Turn off Airplane Mode.

If that doesn't work:

Restart your device. If you're not sure how to do this, follow these steps to restart your iPhone or restart your iPad.

If the first two steps don't work you'll likely need to contact your service carrier.