[Gta04-owner] Cell location IDs

Neil Jerram neil at ossau.homelinux.net
Sat Sep 8 00:24:03 CEST 2012


Neil Jerram <neil at ossau.homelinux.net> writes:

> Radek Polak <psonek2 at seznam.cz> writes:
>
>> Btw those two numbers are nice, but they dont say much. IIRC symbian must have 
>> some database which could translate them to town name.

On my phone those numbers are surprisingly long.  For example on my
phone right now I have 1121/1093926, which in hex is 461/10B126; but all
the references about GSM cell IDs seem to expect 4 hex digits for both
parts.

FWIW I think I just worked out why that is.  I think the explanation is
that the longer numbers are UMTS cell IDs, which I'm getting because of
using AT_OPSYS=3,2.  UMTS is apparently an entirely different network
and infrastructure from GSM, with no obvious relationship between their
cell IDs.  I hadn't appreciated that before.

When my phone boots up, it's initially in GSM mode, and then I see the
shorter GSM cell IDs for a few moments.  But it switches pretty quickly
to 3G.

FWIW (again) it's possible to force the phone back to GSM mode - using
(in QtMoko) Main Menu, Settings, Call Networks, UTRAN, Select Operator,
and selecting an entry with "(GSM)".  But the cell IDs don't revert to
the GSM ones again.  Don't know why; perhaps if I moved into a different
cell, they would then.

> Indeed.  Maybe in future we might connect those numbers to the
> CellHunter/Openbmap/OpenCellID databases, and integrate both using and
> reporting to those databases.

AFAICT, the websites of those databases aren't clear about whether
they're collecting both GSM and UMTS IDs, or just GSM.  Some of them say
"GSM", but also have cell IDs > 0xFFFF, so the "GSM" could just be loose
terminology.  Perhaps for a cell ID database there isn't really any
difference between GSM and UMTS, so long as the database doesn't
truncate the values that are submitted to it.

Regards,
        Neil


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