This number has been calling me up to 20 times per day.  I no longer say anything when answering.  They play music in my ear, and I can hear conversations in the background.  I've tried leaving the phone off the hook when they are on the line - they stay on for a long time (more than 20 min once).  Last time I picked up the phone and slammed it down over and over, then hung up.  i have no idea who it is, or what they want.