Caller: Probably a spam call service

Missed call received from 0488 858 936. Rang back and received "The number you have called is not connected" message.

no idea probably spam.
No answer when received.

There wasn't anyone speaking when received. It just hang up after 2-3 seconds.
Probably it just wanted to confirm my number was valid and it will do more further spams on my number?

never leaves messages

Spam

Most likely advertising; called and hung up, probably checking if my number is valid. BLOCK

Caller: No idea

Unknown caller

Call back couldn’t connected to number