Caller: Scammer ("Tax Office")

Delay after answering, then recorded voice says sternly "This is Australian .... blah, blah, taxation, blah, blah...".
Scammers are so lazy they can't even bother to try to scam you in person.
As a tax official once told me, "if the Tax Office say they can sort out the issue on the spot, it's always a scam. The real Tax Office takes weeks to sort out anything".