I am working over in Australia for a couple of months and got the iPhone 4 on release in the UK on the 24 of June, the only micro sim available in Oz is for the iPad, so bought one with a view of using it for data purposes on lt on the Testra 3G network .... no joy, just keeps coming up with Invalid Sim, but previously was getting a signal, be it weak .... believe it has something to do with the network settings and configuration ..... can anyone help, achieved what I'm after or know for a fact its a lost cause???