I have an older Iphone, I wouldnt use Ziphone as it's said to change things that cannot be reverted, there's a whole load of hoo har about the guy that made ziphone and just about everyone else, anyway for now the only way to use a 3g iphone on a different network is to buy one of the hardware sim changers, these fake your orange sim to look like an o2 one to your iphone, im sure this wont take much longer until it can be broken by software alone. I use this site for the latest software news etc iphonefreakz