The called me today without leaving a message.

called a bunch of times but never left a message

Could hear a room full of activity but caller hung up after a few seconds without saying anything.  I suspect they were phishing for active numbers.
They won't bother me again as the number is blocked.

Called around 8pm last night... I said Hello 3x, but no answer so I hung up.

Same story here. I got two calls about a week apart but I answered neither. I have a world vision child as well. Could be that I suppose - if they want me they can leave a msg.

called my cell today, I didnt pick up, they left no message.