It's the Red Cross, requesting blood donations. I did speak with someone. It's an auto dialer, which is why sometimes there's no one on the line when you pick up. It will keep auto-dialing multiple times per day/week, until you speak with a live person & they can move the next contact date.
I have blocked this number as well as they call every day as other have stated with no message left for me and at times no one on the other end of the line. Today they actually left a message and it is the Red Cross.