No idea who this is. Blocked now!

Lots of calls, no message, now blocked.

does not leave message; calls repeatedly

I agree - called 4 times in 2 days - no message left - will block

Some Police fund raising organization.  Called 5 times in 5 days.  When I asked them nicely not to call me again, they didn't even have the courtesy to say goodby, but hung up without another word.  May be a legit non-profit, but I would not bet on it.