So here's an unexpected and not-much-discussed feature of the 4G mobile broadband trial Optus is running in Newcastle and surrounds right now: unlike commercial 4G services, there's no failover option to 3G. If you're not in a 4G reception area, you get absolutely nothing at all.
To be crystal clear: this isn't a criticism. It's a trial. I can see the logic in only offering connections to the 90-odd sites in the Newcastle area that run 4G: that way, Optus will have a clear idea of peak network load, and customers will be confident that what they're using is always 4G. But it does mean (for example) that anyone who was travelling to work in Sydney on the Central Coast train would need an entirely separate dongle for most of that journey. Their 4G device won't be able to help.
Optus has confirmed that when its commercial services roll out later this year, devices will automatically swap from 4G to 3G if there's no 4G tower in the area. But that's not a feature which will get any kind of workout during the trial. (However, Optus has said it will run internal fallback tests to make sure the option works.)
Lifehacker will be heading to Newcastle this weekend to check out the service, and we'll bring you a full report on how it runs come Monday.