You can also look at the carrier charts I posted here.
And to expand on what the others said, if/when they confirm the BM818-T1 modem as an option (likely from what they have said), that will give full 3G and 4G coverage for all the important bands in Australia. The BM818-E1 modem, which is already listed as one of the modems they will offer, will give full 3G coverage and all but the (unfortunately) most prevalent band for 4G.