Hi guys,
I am a newbie so please don't shoot me with my stupid question. Anyway I have been looking all over but can't seem to find the answer. Is there any prepaid 3G service in Japan? one that you could bring your UTMS phone to use? Any help would be appreciates.

I just put a page about Japan on this site today, but as you can see, from what I could undertand from DoCoMo and Vodafone KK's sites, there is no 3G prepaid offer by now.

But Riiing/United Mobile seems to work well over there.

Last time I was in Japan, about a year ago, I asked if Vodafone had any prepaid SIMs. The answer was, "No." They do have prepaid PDC phones. I'll be back in Japan in a few months and ask again, but I think the answer will still be, "No." But as Effendi said, I have tested Riiing and it worked but seemd to be in a unique pricing zone at (as I recall) 59cts/min for incoming calls.

I am not talking about CDMA prepaid. I am talking about GSM prepaid. Effendi, could you confirm that Riing/United sim works in Japan?

I went to United Mobile page, they don't offer service in Japan.

In Japan there is no GSM, so it's a little hard to find any GSM prepaid or contract there! :D
They have PDC (2G) and W-CDMA (3G), as well as CDMA2000 1x Ev Do (3G, so they say).
The only prepaid available (buying a phone) are on PDC network, which exists in Japan only. Vodafone surely offers some (you find info on this site), I'm not sure about DoCoMo, but probably they do.

United Mobile officially doesn't cover Japan; but UM is virtual operator on FL1 network, and FL1 has roaming agreements with Vodafone KK; DRNewcomb, as well as Stu, used it in Japan, so it works, even if it's quite expensive. But of course you need an UMTS (W-CDMA 2100MHz, the European standard) phone, since there is no GSM there.

I can confirm that Riiing works in Japan if you have an unlocked 2100mhz 3g handset.

It should be noted that it is getting harder and harder to purchase a prepaid set in Japan. Because of concerns that such units have been used by kidnappers in the past, the Japanese Legislature has tightened the standards for obtaining these handsets. Identification is required for these units to be purchsed and most identification has to be Japanese and demonstrate some sort of residency.

Both DoComo and Voda have rental programs at Narita where you get a 3g handset and a SIM for around $6 a day. These phones have free incoming. For short term stays, these units with a callback service might be your best bet.

I can confirm that it worked in Japan last year. Only on Vodafone.

Thanks Stu for your info; Riing has become part of United Mobile, and the United site doesn't have Japan as a coverage country.

Don't worry, FL1 (the main network of UM) has coverage in Japan :)