@markd70: For clarity, is the phone ringing but you're unable to answer it, or are you not receiving any incoming calls? Are you still able to make outgoing calls, and send and receive SMS/MMS messages? If it's the former then, as a workaround, try opening the Phone app > Tap the 3 dots in the top right > Settings > Answering and Ending Calls > Press Volume Up to Answer, and toggle this option on to see if this helps.
To further troubleshoot the issue please open the Phone app > Tap the 3 dots in the top right > Settings > Supplementary Services > Call Barring > Voice Call, and make sure that all options here are toggled off, especially 'All Incoming Calls' and 'All Outgoing Calls'. Tap the back button > Call Forwarding > Voice Call, and make sure that all the options here are toggled off. Now, head to Settings > Connections > Flight Mode, and toggle this off if it is enabled.
If the issue persists, please remove your SIM, give the gold contacts a rub, and put it back to see if this helps. If the issue is only affecting certain contacts, please open the Contacts app, select an affected contact, tap the 3 dots in the top right, and select Unblock Contact, if applicable. I also recommend reaching out to your network provider to see if there are any restrictions on your account, or to the service in your current area.