Whether the call is answered, or the answering machine picks up, there is only a loud, slow beeping noise on the other end.  It hangs up after a minute or two of beeping.  The calls seem to come during buiness hours.  The name on the call display is PPC.  There are several numbers that show up on the call display that give this 'behaviour', each of them beginning with 613-288-.  I will list a few here.