Because information on JCI's popular b-mobile SIMs was scattered all over this blog, I've consolidated everything here. As time permits, I will also compile a separate post comparing other MVNOs in Japan. Yes, they do exist, but none of their product offering are compelling to me, though I hope that changes. For now, I can only recommend JCI's services.
B-mobile is an MVNO using Docomo's FOMA network. JCI is also the MVNE behind VoIP provider BlueSIP and MVNO Rstream. Depending on your usage and needs, the b-mobile SIMs can be much less expensive than Docomo for the same quality of service. All B-mobile SIMs allow tethering at no extra charge.
If possible, before purchasing I recommend trying out their SIMs, which can currently be done at the Yodobashi Akiba in Tokyo all day Friday, Saturday, and Sunday, as well as Monday PM.
Overview of SIMs
Comparison table
Troubleshooting
Hard/firmware combinations confirmed not working
U300
This is a prepaid data-only SIM that is limited to a 300 kbps. The one month version is popular among temporarily visitors because it can be purchased with cash and doesn't require residency status. However, the one month version is not (that I've seen) available in retail stores, though I've seen them in various small corner shops in Akihabara. These SIMs can be shipped to a hotel address and paid for COD. I've also seen them available on Ebay (for twice the normal price). There are also six and twelve month versions and micro and full size versions.
TalkingSIM
This is postpaid traditional cellular phone service with 300 kbps data. It supports mobile number portability (MNP), so an existing phone number can be transferred to this service. Japanese law limits cell phones to residents. There is no micro talkingSIM - only a platinum micro talking SIM.
Platinum
Platinum SIMs are for iOS devices only and provide 1.2 GB of data per month. Speed is unlimited for certain predetermined apps (See Note 6 below the table). Other applications and tethered devices are limited to 300 kbps. There are prepaid data-only SIMs available to non residents and postpaid platinum talkingSIMs. Micro and full size versions are available
Fair
The Fair is a completely unrestricted prepaid data SIM that is charged in 1000 MB units that are valid for either 1) 120 days (4 months) or 2) 30 days (1 month).
Four Month FAIR
This is not designed for heavy data users but can be very economical for those who only need 250 MB per month (a quarter of the charge). Having reliable access to wifi during the day is helpful to ration the bandwidth over a four month period. This is an option for short term visitors who don't mind paying more excellent coverage and speed. I currently use a b-mobile Fair SIM and have a series of posts under the "Fair data cap" label. Fair Micro SIMs are also available
ADDITION: The point at which the four month Fair becomes more expensive than Docomo depends on if you are comparing to the flat or tiered plans, between which there is about a 500 yen difference. Assuming the cheaper of the two prices, about ¥5,500/month, using 658 MB per month with the Fair will be more expensive than using Docomo. (I have only ever used 650 MB in a month with Docomo.)
Comparison to Docomo:
¥8,350 / 1000MB = ¥8.35/MB / ¥5,500 = 658MB
Comparison to Aeon Plan C:
¥8,350 / 1000MB = ¥8.35/MB / ¥4,980 = 596MB
This means that the Fair is not a good deal for someone who uses 650MB with a Docomo branded phone. Compared to the Aeon Plan C SIM, the Fair is not a good deal if you use about 600 MB per month.
1 GB Flat rate
After the initial 1 GB charge is used or 120 days passes, the FAIR can be recharged for ¥3,100 for 1 GB that is valid for 30 days. See here for more information. 1 GB Flat Rate SIMs are now available. These cannot be converted to a FAIR (thought the reverse is true) and the SIM expires 10 days after the charge is used up.
TalkingFair/Talking 1 GB Flat Rate
This adds a voice plan and requires a 1 year contract, though the contract has better terms than other carriers because it doesn't automatically renew. Early cancelation fee is ¥10,500. A 1GB Flat Rate talkingSIM (30 day recharge plan) would cost ¥4,350 per month
Aeon
Data-only
There are three versions of these data-only SIMs. All are postpaid and only available at Aeon retail stores (current list [J] as a google map). The 100 and 400 kbps versions are similar to the prepaid U300 in that streaming is not allowed. The "carrier speed" version allows streaming. B-mobile VoIP service is possible with each of these SIMs. (See here for more details and Note 4 below the table). Micro SIMs are not available.
Voice
There are now voice plans available. 1-year contract required. Other terms are the same as the data-only SIMs. See here for more information.
(aka the BFT)
SIM
|
Cost
|
Voice (1)
|
Speed
|
Tethering Speed
|
Data limit
|
Streaming (2)
|
Billing
|
Residency required
|
Availability
|
Payment method
|
Initial fee
|
Unique public IP (3)
|
Notes
|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| U300 1 month |
¥2,980
|
X
|
300 kbps
|
300 kbps
|
Unlimited
|
X
|
Prepaid
|
No
|
Internet only
|
COD/CC
|
¥0
|
O
| |
| U300 6 month |
¥14,900
(¥2,483/month) |
X
|
300 kbps
|
300 kbps
|
Unlimited
|
X
|
Prepaid
|
No
|
Internet/retail
|
COD/CC/cash
|
¥0
|
O
| |
| U300 12 month |
¥29,800
(¥2,483/month) |
X
|
300 kbps
|
300 kbps
|
Unlimited
|
X
|
Prepaid
|
No
|
Internet/retail
|
COD/CC/cash
|
¥0
|
O
| |
| Fair |
¥8,350/1000 MB
(min. ¥2,087/month) |
X
|
7.2/5.7 Mbps
|
7.2/5.7 Mbps
|
1000 MB/120 days
|
O
|
Prepaid
|
No
|
Internet/retail
|
CC/cash
|
¥1,450
|
O
|
supported phones
micro SIM avail |
| Talking Fair |
¥8,350/1000 MB
+ ¥1,250 for 32.5 minutes (min. ¥3,400/month) |
O
|
7.2/5.7 Mbps
|
7.2/5.7 Mbps
|
1000 MB/120 days
|
O
|
Prepaid data/postpaid voice
1-year contract |
Yes
|
Internet/retail
|
CC
|
¥4,600
|
?
|
supported phones
micro SIM avail |
| TalkingSIM |
¥3,960
|
O
|
300 kbps
|
300 kbps
|
Unlimited
|
X
|
Postpaid
|
Yes
|
Internet/retail
|
CC
|
¥3,150
|
X
|
supported phones
25 min inc. ¥21/30s |
| Aeon Plan A |
¥980
|
X
|
100 kbps
|
100 kbps
|
Unlimited
|
X (4)
|
Postpaid
|
Yes
|
Retail only
|
CC
|
¥3,150
|
X
| no microSIMs |
| Aeon Plan B |
¥2,980
|
X
|
400 kbps
|
400 kbps
|
Unlimited
|
X (4)
|
Postpaid
|
Yes
|
Retail only
|
CC
|
¥3,150
|
X
| no microSIMs |
| Aeon Plan C |
¥4,980
|
X
|
"Carrier speed"(5)
|
"Carrier speed"
|
1.2 GB/month
|
O
|
Postpaid
|
Yes
|
Retail only
|
CC
|
¥3,150
|
X
| no microSIMs |
| Talking b-micro SIM platnium (6) |
¥6,260
|
O
|
"Carrier speed"
|
300 kbps
|
1.2 GB/month
|
O (6)
|
Postpaid
|
Yes
|
Internet/retail
|
CC
|
¥3,150
|
X
|
iPhone 4
|
| b-microSIM platinum 1 month |
¥5,280
|
X
|
"Carrier speed"
|
300 kbps
|
1.2 GB/month
|
O
|
Prepaid
|
No
|
Internet/retail
|
COD/CC/cash
|
¥0
|
X
|
iPhone 4/iPad1,2
|
| b-microSIM platinum 6 month |
¥29,880
(¥4980/month) |
X
|
"Carrier speed"
|
300 kbps
|
1.2 GB/month
|
O
|
Prepaid
|
No
|
Internet/retail
|
COD/CC/cash
|
¥0
|
X
|
iPhone 4/iPad1,2
|
| b-microSIM platinum 12 month |
¥56,160
(¥4,680/month) |
X
|
"Carrier speed"
|
300 kbps
|
1.2 GB/month
|
O
|
Prepaid
|
No
|
Internet/retail
|
COD/CC/cash
|
¥0
|
X
|
iPhone 4/iPad1,2
|
| U300 micro 1 month |
¥2,980
|
X
|
300 kbps
|
300 kbps
|
Unlimited
|
X
|
Prepaid
|
No
|
Internet only
|
COD/CC/cash
|
¥0
|
O
|
iPhone 4/iPad1,2
|
| U300 micro 6 month |
¥14,900
(¥2,483/month) |
X
|
300 kbps
|
300 kbps
|
Unlimited
|
X
|
Prepaid
|
No
|
Internet/retail
|
COD/CC/cash
|
¥0
|
O
|
iPhone 4/iPad1,2
|
| U300 micro 12 month |
¥29,800
(¥2,483/month) |
X
|
300 kbps
|
300 kbps
|
Unlimited
|
X
|
Prepaid
|
No
|
Internet/retail
|
COD/CC/cash
|
¥0
|
O
|
iPhone 4/iPad1,2
|
| TalkingSIM plantinum |
¥6,260
|
O
|
"Carrier speed"
|
300 kbps
|
1.2 GB/month
|
O
|
Postpaid
|
Yes
|
Internet/retail
|
CC
|
¥3,150
|
X
|
iPhone 3G/3GS
|
- These are traditional voice options than have standard phone numbers and support mobile number portability (MNP)
- Streaming includes music, video and voice chat (youtube, skype, etc.)
- I have only personally confirmed this with the U300 and Fair SIMs. This post indicates that the Aeon 100 kbps SIM is behind a proxy, so I assume that the 400 and "carrier speed" versions are as well. I have been told by devs that the talkingSIMs have some "closed ports", which I interpret to indicate a private IP address. I understand that the platinum SIMs are technically very similar to the Aeon Plan C SIMs, so I am assuming the Platinum SIMs are also assigned a private IP address. The easiest way to confirm this is to use MyIP or run netcfg from an adb shell or terminal emulator window and look for an IP of the form 10.x.x.x, which means you have have a private IP address. (Public vs. private IP addressing could theoretically change since public IPs are not guaranteed in the terms of service.)
- B-mobile's VoIP service is allowed with these SIMs, but relying on VoIP with a 100 kbps connection, while technically possible, is not recommended. Different hardware and firmware combinations may produce unexpected results, where sound is not routed properly (e.g., incoming voice being routed through the phone's back speaker, rather than the ear speaker). Service is not guaranteed to work properly on non-bmobile hardware.
- "Carrier Speed" is indicating that the connection speed is not limited from what Docomo customers enjoy, so in general, the speed of the unlimited Fair should be comparable to the Aeon Plan C and Platinum SIMs
- Platinum SIMs give carrier speed only to certain applications (visual voice mail and facetime are excluded):
- Mobile Safari
- App Store
- iTunes (Podcast)
- radiko (recommended 30 second buffer)
- Mobile YouTube
- Ustream live broadcaster
- Mobile Google Maps
- Evernote
- Dropbox
- Skype
NOTE: So far I've got several reports of Motorola phones with Android 2.2 not working with bmobile SIMs. Before buying a SIM for a Motorola phone, if at all possible, please try it first to be sure it works.
There are several important points to consider before buying a b-mobile SIM. If you can visit Tokyo, the Yodobashi Akiba store in Akihabara has a demonstrations of b-mobile SIMs on Friday, Saturday, and Sunday, plus Monday afternoon. You can slip a SIM in your phone and see if it works. (The Shimbashi Yamada Denki demo corner has been discontinued.)
- The phone must be unlocked or be Docomo branded (Docomo phones don't need to be unlocked)
- Only a handful of phones are officially supported (see links in table)
- Unsupported phones may not work at all
- Unsupported phones may work but with several issues including:
- No 3G icon (Nexus One with with 2.3)
- No 3G icon and no signal bars (ht-03a with 2.2)
- "No network connection" error message popped up by browser (does not affect browsing)
- Some apps may not use background data because of an apparent lack of internet connection
- Excessive battery use by radio searching for a signal
- Android 2.3 Gingerbread works best for phones
- Android 3 Honeycomb works best for tablets.
- NTT Docomo and "emergency calls only" are displayed on the lock screen and/or the pulldown notification bar
- There are no SIM card error messages and there is a "080" phone number (viewable from settings)
- Browser redirects to the b-mobile site (wait longer for activation to complete)
Hard/firmware combinations confirmed not working
- HTC phones with Android 1.6 Donut.
- Motorola Atrix (requires this fix)
- Acer Liquid A1 with 2.2 (see here for fix that requires root access and the ability to mount /system as writeable)
- Based on comments below, it seems the Motorola Droid 2 Global on 2.2 may also not work without the above Atrix fix.
Updated to reflect information from comments below and information on new products such as 1 GB Flat Rate and Aeon TalkingSIMs.














