Looking to earn fees by getting tax breaks and concessions. Saving tax is ok, but these telemarketers do NOT like to talk about their fees, which negate the benefit of the tax savings (if any). Mention fees, and the sidestepping begins big time.
These people are telemarketers.

Called me and I intentionally didn't answer. They left a robotic sounding message which simply said 'Good bye'.

Spam

suspect number hung up when answered.

I asked the guy why he was calling me and how he got my number and his back was up straight away and he ended up saying that 'I'm not going to tell you now" and hung up

rang a few times then stopped

Both my husband and I got a call (on our mobiles) from this number, but they won't let the number ring long enough to give time to answer. No messages left. No results found, which leads me to believe it is someone from overseas diverting the call through a fictitious landline number in Australia (Melbourne).
We're in Northern Rivers area in NSW

I called back number (03) 6457 3834 rang 3 times then goes to busy tone.

(03) 6457 3834 rang my mobile & hung up before I could answer, so I called it back from a land line. I got a recorded message that said the number had been disconnected. Not sure how a disconnected number can call me. I wonder if I would have got the same message if I had called from my mobile. Obviously a scam of some sort

rings once or twice then hangs up.