How to use SoftBank prepaid on your US iPhone
This is a quick guide on teaching you how to use a SoftBank prepaid SIM card with your unlocked US iPhone. The reason I’m writing this is because the only information I was able to find was either incorrect or difficult to track down. There was nothing definitive so I’m hoping this will be a definitive guide. First things first: it’s important to note the current firmware at the time of writing this is 3.1.3, though I did all this using version 3.1.2 and modem firmware 05.11.07. YMMV.
This is important if you’re only visiting Japan since Japanese cell phone retailers will not sell you a phone unless you have your gaijin card (which is only obtainable through special working visas). If you visit Japan often-ish like me, I would recommend this method.
Finally, it’s important to know this method will only enable voice and email. Data on a prepaid card is never an option.
Update: iOS 4.0+ has been out for some time now, and while I haven’t tested this on iOS 4 and above (or an iPhone 4 for that matter), I can’t speak to it, however there are apparently some pretty comprehensive instructions (in French, mind you) available on this forum thread at frenchiphone.com (thanks, Julien). Once I can test it out for myself, I’ll redo this guide.
