Japan 2G Band Support

[hakujin]

Anybody know if NTT DoCoMo or Soft Bank offer legacy 2G GSM1900 support?

[yangj08]

No. Their 2G bands are completely incompatible.

[hakujin]

Dumb question right? Thanks.

[IonNuke]

http://gsmworld.com/roaming/gsminfo/cou_jp.shtml

For future reference.... that's the existing bands and services in Japan.

[Chillyman]

Oh you mean just 3G 2100MHz?

[fireshark]

Furthermore, their own 2G services are being phased out anywayss.

[hakujin]

Isn't it also true that some 3G 2100 handsets in U.S. can't be used in Japan because of slight frequency differences?

[yangj08]

Yes. The "2100" in the US has a different uplink band than the 2100 used in the rest of the world. We have the FCC to thank for that.

[hakujin]

Thanks yangj08.

As I understand ATT's UMTS adoption, they mostly use 850/1900 3G independently (meaning up/down on one band; async perhaps?) so not even 2100 3G band. So... at first glance, it would appear to me that NO ATT phone can be used (unlocked of course) in Japan But then I hear conflicting reports that iPhone 3G supports 3G 2100 (specifically: 2110–2155 MHz) which would appear to offer some level of 3G coverage in Japan no, even it's it's different uplink but same downlink?

On the other hand, T-Mobile uses 1700MHz band (uplink) /2100MHz (downlink), and I'm not sure what Japan uses for uplink thought it appears exclusively 2100 band. Would T-Mo phone 3G work in Japan?

These plethora of different bands and slightly different frequencies are definitely annoying in this day and age. One would think it was done after the 2G 850/1900mhz vs the rest of the world's (minus JP/SK) 900/1800, but noooo... dunno why the FCC couldn't just reallocate what ever is licensed on the bands needed, to provide transparency between U.S. and Japan. I swear the mobile companies are in cahoots so they can charge egregious roaming fees on 'compatible radio overseas phones'. It's hard enough picking a decent Smartphone that matches my needs... is it so much to ask for a 3G phone that can be supported in my trips to Tokyo?!

[aw614]

htc makes them

[hakujin]

Well that's great, as I love HTC phones, and will definitely pick up the Touch Pro 2 when/if it hits T-Mobile.

I guess in the U.S. we basically have to look for a 3G Tri-Band UMTS (e.g. 850, 1900, and 2100 MHz bands) or 3G dual band (1700,2100) handset for 3G interoperability between both countries.

BTW, I negated to mention Verizon and Sprint in my earlier post for comparative purposes. Or they even an alternative to this, or not since they use a competing 3G network i.e. CDMA2000's EV-DO, it's definitely a no go in Japan, even in the foreseeable future, am I right? Wait... a sec. Thinking as I type here, but KDDI “au” supports CDMA 2000 does it not?

[hakujin]

ok... perhaps the forecast isn't as gloomy as I predicted as upon further research, I'm finding quite a few U.S. phones that throw in UMTS 2100.

nokia e90, moto razr v3, palm treo 750, Sony Ericsson G900... should all work in Tokyo and, I'm sure there are plenty of others.

yangj08 , you said something about a different uplink (transmit) and I don't disagree with you. I think it's 1920 - 1980 [IMT] and 1710 - 1770 on T-Mo 3G, but it seems that in least in terms of voice, any of the aforementioned and more should be good in Japan, should they not? Perhaps Japan offers the utilization of 2110 - 2170 for both receive and transmit as part of their global agreements with other country's roaming services (can anyone confirm this?). According to http://www.aetherwide.com/articles/roamjapan.html a Sony k610i worked fine in Narita, so I presume all of the above would work as well, else what's the point of offering the 2100mhz band on U.S. phone (minus T-Mo who does a 1700/2100 split and prolly needs it)

[AL9999]

Wow, now I'm extremely confused. Let me make this clearer...

I prefer to think of UMTS using the band numbers the 3GPP designated for them, rather than the frequencies, because of all of this frequency overlap.

Read this:
http://en.wikipedia.org/wiki/UMTS_frequency_bands
Then take a quick look at this (maybe using Google Translate):
http://ja.wikipedia.org/wiki/W-CDMA

The charts on both pages detail the different band designations and the frequencies they use. The JP page is interesting because it notes the operators and the bands they use (the EN page only says which countries the bands are in use in).

Now, to clarify, all of the following networks run UMTS networks in the following configurations:

* Most of the world's networks (in mainly Europe, Asia, Oceania) mainly use Band I (2100), with Band VIII (900) as a backup/booster.
* In North America, AT&T mainly uses Band II (1900) with Band V (850) as a backup/booster; T-Mobile uses Band IV (1700/AWS; not to be confused with Band I 2100).
* In Japan, NTT docomo and SoftBank both use Band I (2100); NTT docomo also uses Band VI (800) as a backup/booster and Band IX (1700; not to be confused with AWS 1700) for congestion relief in Tokyo, Osaka and Nagoya; EMobile also uses Band IX (1700) as its main band.
* In South Korea, which until a few years ago was a CDMA-only country, SK Telecom and KT Freetel now both run Band I (2100) networks throughout the country.
* In Australia, Telstra uses Band V (850) as its main band with Band I (2100) as an alternative band in the main cities; Optus uses Band VIII (900) as its main band with Band I (2100) as an alternative band in the main cities; Vodafone will soon be exactly like Optus (it currently only runs Band I (2100)) and Three only runs Band I (2100).

So yeah, the world is a mess as far as 3G is concerned.

The iPhone 3G supports Band I (2100), Band II (1900) and Band V (850), making it completely compatible with all the world's operator's 3G networks. It will run in Europe (on Band I), in the US (on Band II or Band V using AT&T), in Japan (on Band I, docomo or SoftBank) and in Australia (on Telstra Band V or the other networks Band I).

What you should be looking for is, if the phone supports '2100', it's likely to be the worldwide 3G band, not T-Mobile's band. T-Mobile's band (Band IV) is frequently referred to as either 'AWS' or '1700', rarely '2100' (even though it uses the 2100 MHz frequency). Phone that only support Band IV won't work in Japan at all. But yeah, the only point of supporting Band I in a US phone is for better roaming support. Band I isn't used in NA at all.

Forgot to mention, KDDI's CDMA network (branded 'au') in Japan runs on completely unique CDMA bands as well as Band I, meaning none of the CDMA phones sold outside Japan will work there. Only phones made for KDDI's network will work on it.

Hope this has cleared things up.

[yangj08]

Out of curiosity, why do a couple of band designations sit within each other? Apart from Band VI sitting within Band V (which allows newer DoCoMo phones to use 3G in the US, Canada, Guam, etc), Band IX sits within Band III (despite Band III being called "1800"- presumably providers that eventually use Band III would be able to support inbound roaming from E-Mobile and DoCoMo as well as other future Band IX users). Why not just combine them?

[AL9999]

Because it wasn't the 3GPP that created these band designations, it was the governments of each country that did. Japan's government designated Band I, Band VI, Band IX and Band XI (1500) for use for mobile phones; most of the world designated Band III and Band VIII for mobile phones (after the EU did it in the GSM days) and the US designated Band II, Band IV and Band V for mobile phones. All the 3GPP did was come together and create a nice, organised table to classify them.

So to officially combine them you'd need agreement from all the government regulatory bodies that have defined the bands. It's highly unlikely.