It is a fax machine calling.  It is waiting for your fax to answer, of course if you are not one it just hangs up.' They called me twice today.  Very annoying as if I had nothing better to do than answer a call from a machine.

They call quite frequently and there is never anyone answering on the other end. I'm curious but certain if I allowed it to go to my answer machine if they'd leave a message..

Call at least once a day for the past week. When I answer, it's silent, then they hang up.