Someone from this number has called 12 times in the past 2 days but hasn't left a message.  Anyone know who they are?

They have been calling me as well nonstop!

They have been calling me nonstop for the past week or so. Never leave a message.

Same problem here. Has called multiple times over past few weeks never leaving message. Extremely annoying.

I have received multiple calls, and finally was able to answer the other night.  Some guy started giving me a pitch about lowering my energy costs.  I told him I wasn't interested and to remove me from his calling list.  He said he would, but continued with his pitch.  I hung up.  A minute later, he called back and insisted on knowing why I wasn't interested!  I firmly (and a bit loudly) told him that I wasn't interested, that is all he needed to know, that he is calling me illegally since I am on the Do Not Call list, and to remove me from his records immediately.  Since then they have called back four times, none of which we were home for.  If we get them again, my wife will attempt to get some info on who they are, and I will be filing a complaint and a small claims harrassment suit (it is your right for repeated Do Not Call offenders) if necessary.