I started this test with only 890 MB, as opposed to the full 1000, due to testing skype, tethering, and other high bandwidth applications.
Now there is 861 MB remaining and I have 87days (out of the 120 total) to use it.
This week has seen relatively light data usage. I spent most of the time around wifi and didn't have the need to do any tethering. I consumed the most bandwidth on 5/10 because I was out all morning.
It's too early to make any significant predictions, but extrapolating over the next 4 months based on this week's usage indicates that I'd have a significant portion of the charge remaining when it expires on August 10th. I calculated from a linear fit that I'd have 530 MB remaining 87 days from now, and at this rate would only use a total of about 600 of the 120 day life of the SIM, if I don't use more data.
So I guess I'd better use more data.
And I certainly will, just as soon as the need to tether hits, or as I spend more time away from wifi, for example. I will easily consume 10 MB, half of what I used all week, during a short tethering session. All in all I'm not surprised about this week's data usage.
But I am surprised about something. With data deactivated on the Docomo ht-03a, I am absolutely shocked how long the battery lasts.
I've made very little phone calls this week, and the CPU is set to clock down to 128 MHz when asleep. The charge basically last for a full week.