Earlier quoted context omitted.
Well pretty much any router with a PPPoE client should work then. What is the "free city wifi" thing you referred to that requires the isp provided router?
I suspect he means the schemes where you agree to run an AP other customers can use and in return you get to connect to their AP's while on the move.
Maybe thats just me though. My Thai phone provider gives me global roaming with unlimited data capped at ฿300 a day (about $10 a day). The last time my wife and I came back to Australia together, we had pre-paid Telstra sims. The time after when I came alone for work, I didn't bother, as the roaming cost worked out better than Telstra's shitty pricing, and I still got to use their network.
As for an actual solution, I doubt there is one an ideal solution in this case. Honestly, I would want to need access to a lot of other people's Wifi before I signed up for this type of deal - how sure are you this doesn't give the other Telstra members carte-blanche access to your local network, and how sure are you a judge will accept "but your honour, that could have been anyone downloading those pictures, I have Telstra Air".