Hi All,
Just a follow up on this topic - I was unable to get the DFRobot board to work, so went with a SIM5320E instead, using an Optus (Amaysim) Sim. This unit worked out of the box in the same manner that the 5216E did, so hopefully this info helps anyone looking for a compatible unit for Optus.
I am in Sydney metro, since it appears that where you are in Australia (outback etc) appears to influence the network band in use - whether this is the same for Optus as well as Telstra would require more investigation.
Still determined to get the DFRobot board working… sometime 
Mal
