There was a pause of several seconds between my saying "hello" and the caller beginning to talk. That usually means it's a call center waiting for the called party to go off-hook providing return supervision to the call director that someone has answered, and for the call director to get an agent on the line. I heard someone say my name as I was hanging up. I Googled the number and found it was "Environment America Research and Policy Center" in Boston. Since I've never heard of them and their website solicits donations, I'm guessing they want money.