My husband and I have iPhones that we have unlocked. Will they work using Sim cards in Japan?

Yes I believe there are a few companies you will be able to use it with..

Specifically - SOFTBANK

Yes, as long as you use SIM cards (heh). Adam is right. Soft Bank is the company that carries iPhone here so it'd probably be better to go with them since they have a plan specifically for the iPhone.

uhhhh... there's more to it than just a SIM card. I'm not an expert but I believe the following is correct:

AT&T is a GSM network. GSM is the broadcast standard used in all AT&T phones. Japan is a CDMA country. CDMA is the competing technology to GSM; they are not compatible. So if you have a GSM iPhone, it will not work in Japan. Most of the world uses GSM. CDMA is only found in Japan, South Korea and some USA networks like Verizon and Sprint.

Any telecom experts out there to confirm this? I'll take it down if wrong, but I'm pretty sure this is correct.

Our iPhone that we bought via SoftBank worked beautifully in Japan (of course). When we got back to the U.S., we unlocked it, and it worked fine with AT&T. Well...it worked fine until I (stupidly and without thinking) updated the software to the most current version, and it reverted to being locked. Still waiting for the new unlocking hack, unfortunately. So -- you might be able to use your iPhone with SoftBank, if it's unlocked. Can't hurt to try, at least.

Yeah... that's the thing, it'll work if it's unlocked (as far as I know, anyway, please correct me otherwise) and you can get the contract with the company... but updates, repairs, etc are... n/a.

I honestly think you should sell them and buy the ones here (and you can usually sell unlocked ones for $$$, right?). Softbank usually has a deal where you can get them cheaper than the going rate or free as long as you sign a contract. I know they had it going again recently, and that's how we "bought" ours last year.

That may be what I was wondering. I know SIM cards can be swapped between phones when traveling overseas but not always. I will look into the networks. Thanks so much for that.

Posted By Carolie on 23 Mar 2010 09:44 PM
Our iPhone that we bought via SoftBank worked beautifully in Japan. When we got back to the U.S., we unlocked it, and it worked fine with AT&T. W

Carolie, are you sure it was AT&T? Like I said, they use CDMA in Japan and AT&T is GSM.  I would imagine your unlocked phone would have worked with Sprint or Verizon, but not AT&T.

ThaiGuy -- yes. I bought the phone from SoftBank in Sasebo, used it for a year in Japan. We came to the U.S. at the end of January, and three days later went to the AT&T store. We bought my husband an American iPhone, and just bought me a sim card for my Japanese iPhone. We signed up for AT&T service and immediately began using it on BOTH phones (I'd unlocked my phone the night before we went to the AT&T store).

My Japanese iPhone worked beautifully with AT&T for a month, until I was stupid enough to upgrade the software and "relock" the stupid thing. (I was NOT AMUSED with myself!) We're still using AT&T, have never used Sprint or Verizon.

OH -- not sure if this will make a difference, but it is a 3G phone, and NOT a 3Gs phone.

Elizabeth sorry to barge in but are you saying that Softbank will buy unlocked iPhones?

Oh no, they won't, sorry I wasn't clear. They're just the carrier of iPhones here.

I'm pretty sure unlocked iPhones are still going for a lot on Ebay, etc.

GSM is 2nd generation network technology of digital portable phones.
W-CDMA is 3rd generation network technology of digital portable phones. This technology is also known as "UMTS".

Japanese 2nd generation network was developed by NTT and only used in Japan. That is called "PDC". All 3 major carrier (NTT docomo, Softbank, KDDI au) used PDC, but all are retied. Japan now has only 3rd generation network.

1st iPhone has only 2nd generation GSM. "3G" (and "3Gs") has 3rd generation W-CDMA (bands - 850MHz, 1900MHz, 2100MHz) in addtion to GSM. So 3G iPhone devices are compatible with W-CDMA networks in Japan (Softbank and NTT docomo).

W-CDMA are used in U.K. and Thailand, but they use 900MHz band which isn't compabile with iPhone 3G. (But iPhone can be used in these countries because old GSM network are also available there.)

au (KDDI) also uses CDMA, but different variation which is known as CDMA2000 1x EV-DO. (au's brand name for this network is "CDMA 1x WIN") This is also a kind of 3rd generation network technology, but iPhone isn't compatible with this.

Some countries started to implement 3rd generation network (mostly W-CDMA, few CDMA2000), but all countries except Japan maintain 2nd generation network. Most of them are GSM.

Thanks Okumura, is this gonna be on the test? :-P

Definitely you have to pass the exam to buy Japanese phone :-) - or Japanese (upright) style smile (^_^)

Best site to explain how to get a Softbank SIM to work on your AT&T iphone: http://csi.nfshost.com/2010/03/how-...us-iphone/

The VERY best site to figure out how to unlock your iphone so it can take any carrier's SIM card: http://blog.iphone-dev.org/post/726...rsome-news

To figure out the right MMS settings for Softbank, northing worked for me until I tried "Swirly MMS2" from Cydia.

HI. So Ive lived in Japan about 11 years and SOFTBANK will NEVER unlock your phone.
Now, if you have a 3G or 3GS, you can do custom firmware, and use a software unlock after
jailbreaking using CYDIA and ultrasn0w. You do have to be careful when you update the
software to maintain the unlock. You have to always use custom firmware and a working jailbreak.
AU also will never unlock your iPhone if you leave japan and cancel your contract.
BOTH AU and SOFTBANK will never unlock ANY iPhone under any circumstance.

Ive heard that NTT DOCOMO will unlock their android phones for a 2000Y fee and it will be
always and forever permanently unlocked.

I think for the money you pay, getting a softbank or AU iphone is a waste of money. If you want
an always working iPhone you should buy factory unlocked ones either from the apple store or
the internet so they are always unlocked anytime with any software update.

Your best bet is to stick with android phones. They are very easy to ROOT and getting IMEI
unolock codes are quick and easy with MANY websites.