I called back the number (08) 9345 6815 and reached vm but couldn't hear the company name

don't no number no message .

Called back and got the message "Optus advises that the number you have dialed has been disconnected"

Received a call from this number, picked it up and it sounded like a call centre in the background with somebody speaking. I said hello and the phonecall was terminated. I tried to ring back and got an automated response saying the number is not in service.

called back, didnt connect

Said number was disconnected when I called back