Bit coin and trading scammers.

"Investment opportunity" - haha.
Lots of background conversations, obviously a call centre, and when challenged about being on DoNotCall register, hung up.
When are the "authorities" going to do something about the incessant interruptions from these overseas (and more than likely computerised VOIP) callers, and shut them down or at least block the source ISP?

unknowen call at night , sounds like a call centre

They hung up after I answered

Caller: Says they are Telstra...SCAM

Asked about my Telstra internet access, but when I asked what Telstra internet and they hung up

Harassment caller.

No message left, call back not answered. All the hallmarks of a scam

Another caller who did not leave a message SCAMMER

Caller: (02) 8324 6558

Scam caller, let it go to answering machine

Called by didn't leave message, wanting you to call back.

didnt answer, but appear to have surfaced again after a long time

Warned it could be a potential fraudulent call so swiped without answering.
Message then on phone that the number called but didn't leave a message.
Checked here and see other reports.

Didn't answer, but hung up and didn't leave a message.

Called back and got a recorded message that went on about "for quality assurance blah blah blah" but did not mention who the company was. Fake!

Hung up when I answered

Called mobile - didn't leave message