# Prepaid GSM in Japan

**URL:** <https://boards.straightdope.com/t/prepaid-gsm-in-japan/306788>\
**Category:** Factual Questions\
**Created:** [June 3, 2005, 9:28pm UTC](https://boards.straightdope.com/t/prepaid-gsm-in-japan/306788 "2005-06-03T21:28:19Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![groman](https://avatars.discourse-cdn.com/v4/letter/g/73ab20/32.png) [@groman](https://boards.straightdope.com/u/groman)\
**Post date:** [June 3, 2005, 9:28pm UTC](https://boards.straightdope.com/t/prepaid-gsm-in-japan/306788/1 "2005-06-03T21:28:19Z")

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Hello,

I may be traveling to Tokyo in two weeks on business for a week. I have a tri-mode GSM phone here in California (Sony Ericsson T637).

a) Is GSM coverage on right frequencies available in Tokyo to use my phone? Or is it all CDMA(or something else entirely)

b) I don’t want to roam using Cingular because I’m sure it’ll be prohibitively expensive, especially for international calls(what, like $10 a minute?) Is there a way to buy a prepaid GSM SIM card at the airport somehow(or buy it here in California?) that would work in Japan and would allow calls back to the US?

Thanks.

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**Author:** ![Bag\_of\_Mostly\_Water](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bag_of_mostly_water/32/1029_2.png) [@Bag\_of\_Mostly\_Water](https://boards.straightdope.com/u/Bag_of_Mostly_Water)\
**Post date:** [June 3, 2005, 9:43pm UTC](https://boards.straightdope.com/t/prepaid-gsm-in-japan/306788/2 "2005-06-03T21:43:35Z")

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Japan uses a unique system based on CDMA. There is no “standard” CDMA or GSM coverage, so these phones will not work at all.

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**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\
**Post date:** [June 3, 2005, 10:05pm UTC](https://boards.straightdope.com/t/prepaid-gsm-in-japan/306788/3 "2005-06-03T22:05:48Z")

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You will almost certainly have to rent a Japanese phone. There are companies that will rent a phone with a Japanese number so that you don’t have to roam. [CellHire](http://www.cellhire.com/content/japan.htm) offers this.

As **Ex-Chemist** mentioned, Japan uses totally-unique second-generation mobile-phone standards (the ones comparable to GSM). It does have twothiird-generation networks that allow some roaming, so as a last resort you may still be able to put your SIM card in a rented phone.

My cellphone company’s words on [roaming in Japan](http://www.fido.ca/portal/packages/international.jsp?lang=en#japan).

Also check out [NTT DoCoMo](http://roaming.nttdocomo.co.jp/operators/index.html) and [Vodafone Japan](http://www.vodafone-rental.jp/en/phones_roam.htm). These are the two Japanese third-generation networks.

It appears that Vodafone supports roaming by Cingular SIMS, while NTT DoCoMo supports roaming by Cingular ex-AT&T SIMs only.