Our iPhone SEs have decided not to send or receive call from each other (both are Model MX9E2LL/A running iOs 14.8.1 Incoming calls are going straight to Voicemail but, unfortunately we can't even access our Voicemail
The first thing I did was pop out and re-insert both SIM Cards and noted that only one phone asked that the set-up be completed. Then I
went to this page but got as far as #4 under Check your iPhone settings (Turn off Call Forwarding) but found that Call Forwarding is just a spinning wheel.