My 'solution' (after a few hours of the annoying message but still having service) was to power-down/up my phone. Everything back to normal. iPhone here so it may have been related to the iOS update this week or maybe Telus was doing maintenance.
I got the notice about 6pm EST y'day and saw others reporting it here and on Reddit. Phone would show LTE icon but drop to 3G immediately a call connected, Data speed did not seem to be affected and calls went through as usual. About 10PM EST, I powe...
If a reverse look-up doesn't help, report it to the hospital/care-home management. Good chance an employee is accessing your father's phone while he is unaware/asleep. Keep an eye on his valuables, if any, too.
Look under "Details" and the ++ footnote that confirms what others have said. The ad-copy writers and lawyers need to communicate better with each other.