Does anyone here has experience of an iPhone on a non O2 network and can you tell me if visual voicemail works? If this isn't working, do you know when other carriers (Orange, Vodafone, T-Mobile, Three, Virgin) are likely to get it working? And are any other iPhone features "Not Available" when on these other networks. Looking to buy new iPhone4 but want to check the feature set on all networks before I make the change. Thanks in advance!