I’ve been happily using an iPhone 3g via wifi – everything works great, however when using 3g on the Vodafone NZ network I kept getting ‘PDP authentication error’ messages and no connection. It turns out that iTunes downloads an APN setting to the iPhone that effectively locks the ‘unlocked’ iPhone to an iPhone plan only APN! To set the iPhone to use any APN browse (using wifi) to http://unlockit.co.nz and enter the prefered APN (use ‘internet’ for unrestricted access). Restart the iPhone and you will now find a “profile” setting in the iPhone settings with the new APN. Now you can use the iPhone with any Vodafone data plan – including the brand new casual broadband data rate that works on prepay SIMs ($¹per day for a 10MB per day data cap).