Unfortunately you can't get a SIM in Australia anonymously because you need ID, even with prepaid.
A while ago I moved my SIM into a Hotspot Device for using data, but have learned that that really doesn't do much in terms of privacy, and it creates quite a big hassle for a negligible privacy tradeoff.
I know SMS and cell calls are inherently insecure and not private, but I use aeroplane mode almost 24/7 because I don't recieve many calls or texts.
So, anyone know of a slightly more private SIM in Australia that does less tracking? Thanks.