Yay, the service upgrade has finally happened.
After spending too much time looking for a provider who would upgrade my service to a 1Mbit connection and having to deal with the government changing the funding regime again, I have found a new satellite internet provider, DragNET.
In the back-end, it's still an Optus B3 service using Gilat hardware, but I've now actually decommissioned my SkyBlaster 360e which has been keeping me online since we started our journey (albeit the third actual modem, first one replaced because a firmware upgrade in Dunsborough, the second one was replaced in Mount Pleasant after a storm hit us in Graham's Creek.)
The new modem - which I've had since April 2006 - sitting in a box - is a SkyEdge modem. It gives me connectivity to the same satellite, that is Optus B3 - though I could have opted for D1, I stayed with B3 to keep VoIP connectivity.
So, now with a new service I have a 1Mbit download and a 256Kbit upload with 5Gb of data for the same cost as my previous service. VoIP is actually working and I'm a happy camper.
