[AusNOG] Mobile network-provided time zone

[Paul Wilkins]

The lowest common denominator is the AT+CCLK? command for GSM modems which
returns time & timezone from the GSM network.

Dumb phones afaik don't account for timezone, they set themselves to the
current time at regular intervals without reboot necessary.

Smart phones you have the OS idea of timezone, and possibility for
confusion when the network and OS setting disagree.

Kind regards

Paul Wilkins

On Sun, 7 Oct 2018 at 07:37, Paul Gear <ausnog at libertysys.com.au> wrote:

> Hi all,
>
> In the past 10 or so years, I've used every major mobile carrier's
> network, through both the carrier directly and often through various
> resellers, and one thing remains consistent.  Every year on this
> weekend, when in Queensland, the network-provided time zone changes to
> UTC +11 (Sydney/Melbourne).  This is very handy when roaming overseas,
> but not so handy when it changes your time zone when it shouldn't.
>
> What's causing this?  I know it's not NTP on the handset - I know a
> little about that, and it doesn't include time zone in packets, nor does
> it care about time zone when it adjusts the kernel.  I assumed that this
> feature was implemented on the mobile network side, and the mobile base
> station broadcasts its time zone along with the other information
> handsets need to connect to it.  But I don't know enough about the
> technical side of that to be sure.
>
> The usual suggested remedy when I contact my carrier to complain that
> they're sending my phone the wrong time zone is to ask for the handset
> to rebooted.  Sometimes it works; sometimes it doesn't.  But why would
> it make any difference?
>
> Can anyone shed any light on this?
>
> Thanks in advance,
> Paul
>
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