Thats interesting Cpt Laptop because I have now given Ozemail (having discharged Big Pond, Smartchat and a couple of smaller ones before them) the flick and am soley using One Net. In the past three months I have logeed in first time every, have not had a single disconnect and am getting much faster connect speeds.
I must admit I havn't had a need for tech support and I did have an argument with the dumb chick with whom I set the account up with (when she asked if I had read the terms and conditions, I asked if she had; she said she had not, so I insisted on only talking with someone who had). But apart from that so far it is the best ISP I have used (in Aus).
Have tried Big Pond for global roaming and can confirm it is as big a rip off for this service as it is for domestic Aus use, and cannot comment on ATT because I can't use it where I go.