Suspicious number. Caller ID only says "COLORADO" and I don't have any clients or family or friends in CO. No message left as I didn't answer. Anybody else?

got the same call/situation, on 8-30-12

I received a call from this number (303-219-9765 but no message was left.  I googled the number and found numerous others that have received calls from this number.

I am getting calls from this number to, for the last few days.. and they don't leave message

Received a call from this number (303) 219-9765. He was aking for the owner by name (mispronouncing it of course)
I asked for his name and the company he was calling from. He said his name was Adam calling from Swan Energy. Did not sound happy that I asked.
I placed him on  hold. Upon returning to him and informing him that the owner was not interested he spoke to me in a very stern tone of voice as if he was mad. He was telling me that he(owner) did "not know what it was about, BUT FINE!" and hung up on me.