I get a call from a different number every day of the week with a pre recorded message stating that I've won some prize. The message goes on and on so I usually just hang up. I've never given anyone this number as the phone belongs to my employer.
Do everyone else a favor and file a complaint with the FCC to get these jerks shut down:
http://esupport.fcc.gov/complaints.htm
They actually do investigate issues like this and shut people down.