I always used to ignore unknown numbers until my old mum went into care a few years before she passed, as I had PoA I just had to answer everything in case it was social services, care home, doctors etc. always made for an unpleasant few seconds until you knew who it was calling.
I still haven't got back into the habit of ignoring the landline, but mobile I always do and then google the number.
calls are usually a 50/50 split between "our records show you were recently in an accident" or "we've detected a problem with your computer"