I received a call from this number at 8:30pm on Oct 3, 2008. I lumbered over to the callerid to see that I did not recognize the number. I picked up and then hung up the phone. This is the second or third call. No message is ever left.
When I feel like it I will answer and work them if possible, but I expect it will be only a recording.
I agree with Lone Star, that a computer hook up to screen calls, like Spam filters would make a million. I have heard of devices that play a recording that says, If you want to complete this call, rekey the last four digits of the telephone number. A friendly caller is inconvenienced, but is able to get through. An automated dialer will never get through.