[Gpephone-devel] GSM time updates and UTC/locale/TZ

[Joshua Layne]

Hi all,
I have been thinking about this for a bit (mostly in frustration towards my current WM2005 phone because it doesn't do this), but basically, any GSM phone I have ever had except my current POS (Ericsson and Nokias, mostly) has been able to pull time from the cell towers on a GSM network and automatically update the time on the phone (usually with a user prompt: "The local time is xxxxxx, update?").  Windows Mobile does not do this (surprise!) and so on a battery failure, requires you to reset time and date, screws up the call log (which has a time/date stamp), etc...

My thinking is that this is a fairly easy problem to fix.

I added a few comments to this page: http://www.linuxtogo.org/gowiki/GpepeTodo?action=show

but I wanted to provide more detail and a brief use case of _desired_ functionality here:

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I live in the Bay Area, CA, USA (Pacific TZ).  We are currently in DST (thanks to mister bush) and so our local time is currently GMT -7 (? have to say I always get confused on this.... normally GMT -8, but with DST, we are +1 hour, I think...).

I have a calendar entry for a meeting that starts monday at 8AM PDT.  It is stored internally in my phone calendar as Monday at 3PM (15:00) UTC and when I view my calendar in San Francisco, shows as starting at 8AM on monday (PDT).

I get on a plane and fly to New York on Sunday night.  When I get off the plane and turn my phone back on, I am prompted that the local time is 6AM EDT (it is 3AM in SF) - Do I want to update my local time?

I click 'yes' and my _locale/TZ_ is updated to Eastern Daylight Time.  The internal UTC time (provided there is no gross difference, say a few milliseconds - standard NTP-like functionality) is not updated.

When I view my calendar, I now see that my meeting is at 11AM EDT (note that the internal calendar storage time did not change at all) and am able to call into my meeting a little sleep deprived, but at the correct time.

If I now receive an invite for another meeting, the calendar translates to UTC (probably from senders TZ settings) before inserting the meeting into my schedule.
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Sorry if this is too much "user land", but I figure if I wait until GPEPE is fully built, it'll be too late :), Also - this may be a trivial problem and already how everything works but when I reviewed the architecture, I did not see any interface specified between the RTC and GSM, unless this functionality is mediated by 'atd'.  With most modern phones and towers, this could be accomplished with standard NTP functionality for the UTC internal clock, but servers are not location-aware.  That is the benefit that the cell towers have with GSM.

Comments, thoughts, flames?

Thanks in advance,
Joshua Layne