How do you stop these annoying phone calls

called several times today.
just a few minutes ago I answered and male caller asked for my wife by name but mispronounced last name - I could hear call center type noise in the background - when I asked who was calling he said "her boyfriend" - huh?
I asked several times and got the same answer then he hung up - what the F***? anyone else get a call like this? what is the point?

All week long this 978 000 0000 keeps calling and there is never anyone on the line.  It has happened 3 times today and they have called all week long.  It does sound like a call center but no one answers.  How can this number be stopped.

Called 11 times yesterday. When I answer all I hear is a beep.  Already called 3 times today. All that shows up is Massachusettes call.  Getting really pissed!

Received about a dozen of these calls over the weekend. No messages were left on my machine and most of the time when I answered I heard nothing on the other end.  I just answered yet another call from that number and the woman on the other end identified the organization as the "League of Conservation Voters" and wanted to know if I was voting for certain candidates within Massachusetts.