I HAVE BEEN GETTING THE CALL ON MY CELL PHONE LATELY TOO.  I CALLED BACK AND LISTENED TO THE MESSAGE.  IT SAYS "THANK YOU FOR CALLING.  IF YOU KNOW YOUR PARTY'S EXTENSION DIAL IT NOW."  THEN IT HANGS UP ON YOU.  I TRIED PUTTING IN ANY NUMBER, THE # SIGN AND THE * SIGN.  AS SOON AS YOU PUSH A BUTTON, IT HANGS UP ON YOU.