EDIT: added a new label, "Fair data cap" for all posts about testing the B-mobile Fair SIM.
Cell phone service in Japan is expensive. I have spent approximately ¥100,000 for unlimited data over the 17 billing cycles that I've owned an android handset.
However I don't need an unlimited plan given my personal usage. Until now though, the only economical way of using mobile data on a smartphone was an unlimited plan, which costs in the area of 5000 to 6000 yen per month depending on contracts, carriers, and discounts. This is because per-packet charges add up quickly, topping ¥100,000 in just one month.
I've been testing a prepaid b-mobile Fair SIM over the past few days. This SIM is officially on sale today. (See below for a quick review.) It is a data-only SIM that comes with 1000 MB of data for ¥9800 initially and ¥8350 for each 1000 MB thereafter. While the price per gigabyte is high compared to other countries, it is valid for 4 months, bringing the minimum monthly cost to about ¥2000 per month if you average only 250 MB bandwidth usage per month.
Hypothetically, if I had purchased a b-mobile Fair SIM 17 months ago, and only used 250 MB each month, three additional charges (every four months) would have been required, costing me ¥34,850, which is about one third of the total cost that I actually paid to Docomo from November 2009 to March 2011. I would have just charged the SIM at the beginning of this month, which would have me covered until August 2011. That is nearly two years of data service for ¥43,200.
But is this scenario realistic? For me, close but not quite.
I tallied my actual usage over the past 17 months, I consumed a total of forty-three million, six-hundred thirty-seven-thousand, and one-hundred fifty-one packets. (43,637,151), or in human-readable output, 5.2 gigabytes (To put this into perspective, 5 GB is the amount allowed in one month for Docomo's Xi LTE data service, without incurring additional charges.)
I primarily use Google maps, train schedule apps like jorudan, an RSS reader, and Gmail. I don't download podcasts over 3G, nor do I watch youtube or use VoIP. I do tether to my notebook but certainly not every day and not for extended sessions.
My usage is shown in the graph below. The blue is my monthly usage in gigabytes, and the green is the cumulative usage in megabytes, with points plotted every 4 months or 1000 MB, whichever comes first.
For the first eight months, I would have not used the full charge. In fact, over the first four months, I only consumed 551 MB, half of the allotted bandwidth. I used 967 MB over the next four month period. My subsequent data consumption was significantly higher and would have required a charge every two to three months. Over the 17 month period covered in these bills, I would have paid a total of ¥51,550. However, in reality I paid ¥101,745 to Docomo (17 months at ¥5985).
Voice Not Currently Included
As currently available, this would have required carrying around two devices, one for voice and one for data. At this point in time, I have no information regarding what other services with which this data SIM could be bundled. B-Mobile offers both traditional voice (talkingSIM) and a 050 IP phone service (Mobile IP Phone), though the latter is limited to only the IDEOS currently. It would be good to see this "Fair" SIM bundled with either or both of the above voice options.
The zero-five-zero IP phone would probably be the least expensive for consumers but would likely be more challenging to properly implement given the five versions of Android currently in the wild, not to mention all the carrier/maker-specific firmware builds. A traditional voice option would be easier to implement and also fix some of those niggles we see on Android, but it would likely come with relatively higher service fees.
B-Mobile FAIR SIM Performance
The SIM is just as fast as a normal Docomo SIM. In fact it is identical in outward appearance. I have used it flawlessly with skype over a 10 minute phone call. There are no filters, so I can use non-docomo handsets. The relatively slow uplink is because Docomo has suspended hi-speed uplink (HSUPA) in Kanto and Tohoku following the March 11 quake and tsunami
However it lacks a circuit switch component which causes some issues with Android firmware. First off, HTC handsets running 1.6 are incompatible. Next, the 3G icon does not display. On my ht-03a (HTC Magic) running Android 2.2, not only is no 3G icon displayed, the signal strength indicator has no signal (an "X"). On Android 2.3 and the Nexus One, the signal strength icon works as expected, as can be seen in the above and below screenshots (Gingerbread displays a green signal icons when connected to Google servers). When starting up a new browser session, the native browser throws up an alert saying there is no internet connection when there actually is, and as you can see below, the page is loading just fine.
As far as lack of features, I am not sure if this is just an issue with Android, or with HTC, or with the SIM as provided by Docomo, but I cannot use network based location and time information.