Obviously a scam, but had fun wasting their time by asking random questions, he eventually just hung up, aha

Had call from this number also, no message left and could not call back as Optus said number is incomplete try again. WTF these morons.

called back. Optus advises the number is incomplete! nuisance call

Received call, I did not answer, called left blank voicemail.
Cannot call back number as automated network message advises that the number is not operational or is incomplete!

Screw these dodgy bastards!!

Blocked and deleted the number