T-mobile certainly never used to charge if one exceed the fair usage, however in the dongle they did cap me when i once went over the 3gb limit, this meant i was only able to navigate sites as the speed was something like 15kb.... however in recent times i have heard rumors they been trying to quietly change this unlimited broadband policy, so is best to check first, this all seem to have started since the orange merger, is really a shame they also seem to be trying to go down the same road as all the other failed business modules. I personally have not received any information about this but then i have not been using the service other then to quickly check out a hand full of pages when on public transport.