How can I use a foreign SIM in a Japanese Apple store bought iPhone 4s?
Recently I bought an iPhone 4S from the Apple Store in Ginza (I have just moved to Japan) and took it with me on holiday to Australia. Not wanting to pay extortionate roaming charges I bought myself an Australian Alstra SIM and put it in my phone. My phone kept saying that the SIM was invalid. We checked that it was fine in other phones and came to the conclusion that for some reason my phone would not take it. The Apple store in Sydney then told me that my phone was locked, I told them that this should not be possible as l had bought the phone from the Apple Store. They said there was nothing they could do.
I am very angry because it looks like I have been sold something that I do not now own. Is it possible to get iPhones in Japan that will support other networks (ie have I been sold a dud) or, if not, can they be unlocked (I'm going to be going to the uk soon and will again want to put a local SIM in)?
Thank you for you time and the support that Apple seems unwilling to provide (I have already asked these questions at the Genius bar and received shrugged shoulders)