[tz] Cellphone tz updates often not happening in Israel

enh enh at google.com
Tue Sep 24 17:11:56 UTC 2013

the NITZ string doesn't include an olson id. if you look at
GsmServiceStateTracker.java or the CDMA equivalent, you can see the
heuristics for turning a gmt offset, country code, and "is_dst" flag into
an olson id. (actually, every part of the NITZ string is optional.)

cell towers can be misconfigured, which adds to the fun. plus there are
places like the canary islands that don't have an MCC and don't share a
time zone with the country that they share an MCC with.

On Tue, Sep 24, 2013 at 9:42 AM, Dennis Ferguson <
dennis.c.ferguson at gmail.com> wrote:

> On 23 Sep, 2013, at 16:32 , L. David Baron <dbaron at dbaron.org> wrote:
> > On Monday 2013-09-23 13:07 -0700, Paul Eggert wrote:
> >>
> >> end users in Israel.  Many cellphones running Android,
> >> BlackBerry, iOS, and Symbian were still based on tz release
> My previous phone was a Symbian phone.  I wouldn't update it
> since that generally made it worse than it already was...
> > It also seems odd that these phones didn't have their time adjusted
> > as a result of receiving NITZ messages from cell towers with the
> > correct UTC offset.  I thought that using time and timezone
> > information from the cell network was the typical default
> > configuration on smartphones (which makes having an up-to-date
> > timezone database less critical).
> >
> > Are there carriers in Israel that don't broadcast date and offset
> > information from their cell towers?  Or were the carriers
> > broadcasting incorrect data?
> GSM towers traditionally had no idea what time or timezone it is,
> and many (maybe most) GSM and UMTS base stations still don't.  NITZ
> isn't very common.  I think the "TZ" part of NITZ may have been
> invented to solve a problem specific to American carriers, that
> they were deploying GSM into a market where the competing digital
> technologies (CDMA and IS-136 TDMA) could set the time and timezone
> on the handset and didn't want their GSM service to not have that
> feature too.  I've seen the "NI" part of NITZ, without the TZ part, in
> use in China (despite what the Wikipedia page says) to identify the
> "area" the tower you were connected to was in, since they used to
> charge people different prices for calls in and out of their "home"
> area.  In any case, outside of the Americas it is fairly rare to
> find a carrier which provides this service, so smartphones seem to
> often include plain old NTP and time zone files as a fall back while
> dumb phones need their clocks set by hand.
> Note that in the US mobile phone base stations always know what
> time it is since they pretty much always have GPS receivers, for
> E911 positioning if not for network time synchronization.  In
> many other countries, however, it is considered a bad idea to
> allow your telecommunications infrastructure to become dependent
> on a service owned and operated by a foreign military so they
> are less likely to do this.
> Dennis Ferguson
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