WHO IS THIS

Caller ID said Seattle WA.  no message.

I answered, after 30 sec they then hung up.

Caller was "Linda" with "Home Service Advising Heating and Cooling" offering to clean all of our heating ducts, dryer tubing, and servicing our furnace for the special price of $45 to our "our previous customers" .  I didn't recall the name.  I did schedule an appointment.  After hanging up I did a little research online and learned about air duct cleaning scams.  I decided it best to cancel the appointment so I called the number back.  It had only been about 5 minutes but the number had been disconnected.

After I answered, I heard a chiming sound, followed by a female voice that just said good bye. What exactly is the point?