Got three calls from this number 330-405-8674 today and a 4th while writing this note :) Indeed it's Comcast and sure enough they're confirming a service appt that I set up yesterday for later this week. I asked her why they don't leave voice mail and she said that they were instructed to only do so after the 3rd attempt. And technically I answered their first call but found no one on the line (or my cell reception sucked) so I hung up.
She said that their auto-dialer was "aggressive" and that it didn't yet have some kind of greeting that says "please on the line, while I connect you..." or something to that effect as the call is switched over to an operator.