I doubt that more than one in a thousand (or ten thousand) complaints will result in any FCC action unless the FCC is specially funded to support these actions (which in this economic climate is highly unlikely). The telemarketers are just playing the odds.
I had an old FAX machine which used coated paper on fairly small rolls. For a while I regularly submitted complaints about SPAM faxes, probably about 20 in all, supplying all requested information and enclosing a copy of the fax. I heard nothing until 3 or 4 months later when I received an envelope from the FCC with a single sheet titled "How to submit a complaint to the FCC" which had nothing at all to do with SPAM faxes.
Based on my past experiences, whenever I now see the Belkin name on an electronic product I turn around and run away as fast as I can.
Nothing ever becomes real until it is experienced. - John Keats