Has been calling multiple times daily, never leaves a message. I have answered a time or two and nobody said anything.

same as others, multiple calls and no message.  I've not been able to answer but will try to next time and add another report.

I think it's the Red Cross. Likely calling for blood donations...

It is the Red Cross.  I donate blood and they call to try to reschedule me all the time.

Calls several times a day.  Red Cross probably.  Which btw, if you call and ask them to stop the calls, they will tell you that those calls come from individual donor groups and that you need to call them directlyto request stopping the calls.  Problem is, there are dozens and dozens of these groups.  Very frustrating.