No Public IP Addresses are available via 4g - therefore not static IP addresses are available.
Only exception is certain high level corporate plans - and they are well out of most users price range.
That's what I thought...but...
There's this article on the Optus page that says otherwise:
Article isnt that great, you can get a public IP on 3g and even a static IP on that (on a select few business mobile plans)
As soon as you connect to 4g all thats no longer valid.
We should probably update that support page. It's a bit vague and doesn't offer much detail.
@Unchained_Pat is correct. We can only provision static IP's on 3G mobile & mobile broadband services.
It's not something that's available on our 4G network.
Static IP is currently available on our Mobile Broadband Plus plans.