I bought an iPhone before moving to Japan in hopes of using it here, but was surprised when nowhere would sell me a SIM card. The iPhone that I bought was originally a Japanese iPhone to begin with, so I thought it would be a piece of cake.

Well I underestimated the amount of screwing around I would be doing thanks to SoftBank. In the end I had to buy a whole prepaid phone in order to get a prepaid SIM (technically USIM) card, for which I would have needed a 外国人登録証明書 gaikokujin touroku shoumeisho, a Gaijin card, had my girlfriend not filled out the paperwork.

If you need to get your hands on a prepaid SIM, this is probably the best way, though there are a few success stories of people buying just the SIMs themselves. But it is rare and will take a lot of searching around different SoftBank branches. Hell, even finding a store with a prepaid card and phone will take a little searching.

Anyway, I got the USIM, and as my iPhone is Jailbroken and unlocked, I tried throwing it in there. But unfortunately, no love. After a little internet searching and a lot of conflicting information, I decided to give it up and just use the damned SoftBank prepaid phone.

Fast-forward about three months, to my prepaid phone completely dying. I took it into SoftBank and they confirmed that it was screwed. Thankfully the SIM was still fine. Thus started my 6 hour journey to getting the iPhone to work here. My results were largely produced by trial and error, but it eventually worked out.

So, in order to hopefully save someone else a lot of wasted time, I'm gonna recount what worked for me. Your situation may be different, but I imagine this should work for most iPhones. For reference, I am using an old iPhone 3G running firmware 4.1, Jailbroken and unlocked. As far as I know, you can't do this for iPhone 4s, because the size of the SIM card is different, though I have heard of people manually cutting SIMs to make them work.

The setup

First you need the prepaid USIM. This is white in color, with the silver and white SoftBank logo and the word Prepaid in black.

As I mentioned, you will probably have to purchase this along with a SoftBank prepaid phone, which will set you back about １万円, 10,000 Yen, which should include a ３千円 3,000 Yen prepaid top-up card. This is different to real iPhone SIMs, which are black, and some other SIMs which are grey.

When comparing it side-by-side with an older SIM card, or one from your own country, you may notice some design and size differences. I thought that my initial problems may have been caused by this, but no. The iPhone (3G and 3GS at least) is compatible with the SoftBank prepaid USIM, no matter what people tell you.

Next, you need to Jailbreak and Unlock your iPhone. I won't get into how to jailbreak here, but I would recommend GreenPois0n. A guide can be found here

Apparently it is possible to use this regular sized SIM in an iPhone 4, which takes a micro-SIM. You can find videos on YouTube telling you how. It involves cutting and you only get one chance at it, though. Search for "Mini SIM to Micro SIM."

The Unlock

Once you are jailbroken, you need to Unlock your iPhone so that you can use the SIM of a different carrier. There are a few ways. You may have bought a factory-unlocked iPhone that can be used anywhere, or you might have to use an unlocking SIM or software. Personally I used the unlocking software ultrasn0w. This can be found on Cydia on a jailbroken phone.

Whether or not your iPhone is unlockable depends on your "Baseband" version. Here is a simple guide. If you have trouble, leave a comment.

Once you have unlocked successfully, you should be able to insert your USIM and get the phone services working. If not, try enabling 3G and Cellular Data in Settings > General > Network. I was just about to give up before I tried this. To test your phone capabilities, give 1400 a call. This is the SoftBank prepaid service number. At this point you should also be able to send SMSs.

MMS

If we want to use SoftBank's MMS service (that is, email on the phone), we have to first set the email account up using a regular Japanese phone. Pop your SIM in another phone and go through the options. Once you have acquired your email address, write it down and return your SIM to your iPhone.

In order to use MMS we have two options. One is to use a third-party software called SwirlyMMS 2. A guide for this can be found at this website, and a copy of the important file here is below. Open this file in your iPhone browser (using wireless).

Softbank MMS.mobileconfig

The option that I chose, however, is to use the iPhone's native messaging application. In order to do this, we need access to the "Cellular Data Network" menu under Settings > General > Network (depending on your language preferences, this may be called "Mobile Data Network"). If we can get here, we are almost done.

If, for some reason, this menu is not visible to you, you are having the same problem that I did. And there are a few ways around this. One, the most simple (but it didn't work for me), is to remove your SIM card while the phone is on, wait 10 seconds, and put it back in. Then the menu may magically appear.

The other way, however is to download another Cydia program called Supreme Preferences 3.0. This is a paid program, but let's just say there are ways to get what you want for free. Here is a guide to enabling the Cellular Data Network menu. You will need to get the Cydia app WinterBoard as well. You may need to exit the settings menu and go back in for the changes to be visible.

Once you have access to the Cellular Data Network menu, we will need to change the settings inside. My Settings are as follows:

Cellular Data:

APN: mailwebservice.softbank.ne.jp
Username: softbank
Password: qceffknarlurqgbl

MMS:

APN: mailwebservice.softbank.ne.jp
Username: softbank
Password: qceffknarlurqgbl
MMSC: http://mms/
MMS Proxy: smilemms.softbank.ne.jp
MMS Max Message Size: 307200
MMS UA Prof URL: -BLANK-

Just copy everything there into your settings. Now go to Settings > Messages and hopefully at the bottom you will see "MMS Email Account." In here put your phones email address that you wrote down earlier (probably in the format xxx@softbank.ne.jp).

And that should be it. If you have trouble with the second method, perhaps first try downloading the APN settings on your phone (From KAZUYA's blog, or the copy I have) and then later changing them through the "Cellular Data Network" menu.

If you have any questions, drop in a comment!

Here are the other sites that helped me in some way understand how to do this:

iPhone Hacking Guide
Gaijin Pot Forums

UPDATE 21/06/11 Apparently there is a problem with Supreme Preferences. It will lose its MMS settings if the iPhone is powered off. This means you will have to spend a minute and type them back in. Annoying, I know. I'll keep you posted if there's a better way.

UPDATE 04/07/11 Another way to get you Cellular Data options to show up is to add:

<key>APNEditabilityTypemask</key>
<integer>5</integer>
<key>AllowEDGEEditing</key>
<true/>

to the carrier plist file, on the 5th line. You will probably also want to install the Commcenter patch from Cydia first to make it so that your settings don't get reset every time you reboot (well, hopefully anyway). I'll note that this method didn't work for me, however.

UPDATE 14/02/12 Just noting that I now use a contract iPhone 4, but am still happy to help out those struggling with this. I hope the comments will shine as a beacon of light for those who are frustrated by this!