I don't accept calls from withheld / private / unknown numbers, and still won't take the call if the number is displayed and I have any doubts at all.
The world might have changed, but people / organisations needing to contact you on a legitimate basis, can still use email / paper mail.
Despite the obituary being written, paper mail is still de rigeur for any correspondence from official state / governmental organisations.
The rule is simple really - if it seems fake/dodgy, then it probably is. Hang up on the call / delete the text and phone the listed number for the organisation in question, to check things out.