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i've just unlocked my phone in Australia to use an Australian sim...phone calls, wifi, whats app all work ok but no data available, yes data is switched on and have tried restarting...any help welcome
Normally, when you insert a SIM, the device should have the necessary data settings pushed to it and there should be a notfication that this has happened. If you go into Settings, Mobile Data (and possibly More), open APN Settings and see if the relevant one is there. If it is, make sure it's the default. If it isn't, back out and look for a Get Settings From Provider option. I'm not sure of the exact location, but there aren't too many sub-menus in this section. Tapping it should pull the settings down.
If you're using a local SIM, it shouldn't be necessary to have Data Roaming turned on, but it might be worth giving that a try.