iPhone 3G: can I use it in Japan?

you should be fine, only unlocking will be the problem....

You will be paying the Early termination fee here, but the service provider or the apple store in Japan should OFFICIALLY unlock it for you from AT&T and lock it to Softbank.

That's incorrect, you cannot use even an unlocked iPhone with Softbank because Softbank seperated the iPhone SIM from the rest of its handsets and the SIM is only available through a iPhone specific contract and plan which factors in the cost of the iPhone itself as part of the monthly fee.

You can't get a properly provisioned SIM without that contract which is only available with that specific contract. They explain this to you in an itemization they do during the contract signing process and explain this incompatibility between the iPhone SIM and other handsets.

I can also confirm this as I have 3 non-iPhone Softbank phones and 2 iPhone 3G handsets and swapping SIMs results in a SIM not recognized error both ways.

So probably the best bet is to sell your handset before you leave and just get a new one in Japan. Heck, there will maybe even be a new and improved iPhone my then anyway.

Unlocking the phone wont help either as you still need to get a properly provisioned SIM from Softbank which is not freely available without a contract which is not available without the phone itself being provided by Softbank.

Also, I don't think the cell portion of the iPhone would work in Japan as Japan has it's own "network". I did some research on this last year as I fly to Asia often and wanted a phone that works world wide. At that time I learned that I would need a "Quad Band" phone and at that time there were only two phones, one from ATT (8525) and one from Blackberry. I can't remember all of the technical details but as far as digital networks Verizon and Sprint have one type of network that's good only in the US, T-Mobile and ATT have another type of network that's good most everywhere else in the world, (Europe, South America etc) and then Japan has it's own digital network. Someone explained that Japan's digital network is the next generation.... Anyways, as far as I know the iPhone is not a Quad band phone. I'm not sure if the iPhone would be usable in Japan using the analog network. Again, I apologize for being vague and hope that I'm not completely wrong but my point is to be sure to determine if the iPhone can even get on any of the networks available for cell phones in Japan. I would assume that the wireless internet portion of the iPhone would function normally..

Well the iPhone 3G phone is itself is fully compatible with Japan's cell network. The problem revolves around differences in how the 3G network is accessed on the iPhone 3G vs a typical Japanese handset which is indirect and traffic is usually proxied through a server on the carrier side that formats the content for the handset BEFORE it reaches the handsets browser.

The iPhone needs no such filtering and has basically a clear shot to the internet for every application run on it while every Japanese handset I have ever owned did not have the same access to the network.

So for this privilege, you pay more and a flat fee for data unlike other Japanese handsets which are typically metered using packets sent and received (old school). This difference meant the new separately provisioned iPhone specific Softbank SIM was a must for the purposes of preventing the SIM to be used by a phone that had comparable direct internet capabilities like the iPhone such as a Nokia and perhaps to prevent someone from using a metered Softbank 3G SIM which would allow an unlocked iPhone 3G to freely access the data network without an iPhone specific contract.

Actually the cell portion could work just fine on an unlocked iPhone 3G but the 3G data may not, or it would be metered which would mean stratospheric data fees. But I suspect it won't be able to connect at all on the data side. We will only know the answer to that once the iPhone 3G is unlocked and a non-iPhone 3G Softbank SIM is put in.

Thanks for the helpful tips, japlander.

Curious what your (or any other readers') thoughts are about the possibility of using an unlocked iphone on E-Mobile? Among the Japanese carriers, E-mobile is by far the most modern -- in terms of providing a simple wireless data pipe. Their flat rate monthly plans are reasonable and I've been happily using their OEM'd Huawei E220 USB modem for a while now.

Of course, the iPhone 3G wouldn't be able to access E-mobile's 1700MHz spectrum, but they've got plenty of service at 1900/2100 right now via the DoCoMo MVNO deal. I'm not even sure if some of their equipment even has a 1700MHz radio...

Anyone see any potential problems with this idea?