Had 2 missed calls from this number this weekend--Nov 1 and 2 2008.
I think in the telemarketing world, they use automatic dialers, and sometimes if you pick up real quick, there is a pause. I think it is because the telemarketer is expecting a cue, and doesn't hear it if you answer your phone too quickly. Also, if you don't answer, the machine starts to call the next number. That is why they don't leave messages--wastes too much time.
I just got the call from these mutts on my cell phone. I don't wanna talk to these guys, so why call me. I tried calling back and "They do not accept incoming phone calls at this number".
Same thing happened to me. They seem to call every few days. I have not answered because I don't recognize the area code. After reading the comments here, I think I will continue to ignore them. :D