Hung up when I answered. no message.

Came in while on another call. Disregarded. No msg left.

I get calls all the time. I never answer. Today I redialed. I got the recording 'please stay on the line, your call is important to us.'  So they're legitimate enough to connect to incoming calls.
I'm going to block the call for a few months. That usually works. They give up.

Foundation for first responders and fire fighters. Hung up and blocked.