I am in Sydney today and my phone is connected to "MobileNet". It works ok for voice and I can see "E" showing there's an EDGE service available (no I can't connect to Telstra mobile network with this test handset).
It seems data connections are not allowed. Does Telecom have data roaming agreement with MobileNet at all? I can't find a company with this name - it seems to be a Telstra service.
Any more information?