News item: Cellphone Calls Blew CIA Cover

Someone take a look at this article and check me on something.

http://channels.netscape.com/ns/tech/package.jsp?
name=computing/cpvert/wiredteens

"Unless the power or the wireless antenna is turned off, a mobile phone
remains in constant contact with the nearest cell towers even when it's
not being used for a call. Information processed by the cells can be
used to precisely locate or track the movements of a phone user."

"Since a phone is served by several cells at any given time,
investigators can easily triangulate the location of a device, Errico
said. In an urban area, where the network of cells is dense and
overlapping, such tracking can have a margin of error of just a few
yards."

This doesn't sound right but my GSM knowledge is somewhat limited. I
know for TDMA phones there is a "last known cell location" maintained in
the system to speed up the next call but I thought it was only updated
when a call is placed, received, or ongoing, or when the phone registers
on a new system when roaming. On the next call the system tries that
cell first then hits the entire system. If there's no call in progress
does the phone even transmit to the system for a simple cellsite change?
How different is GSM?

With "last known cell" the best someone could do IF they had the phone
number was to find out where the phone was during the last call. If it
hadn't been cleared for some reason. To locate multiple unknown phones
they'd have to 1) record a log entry for all accounts every time the
cellsite changes and 2) analyze the log over time to get a list of all
phones that were updated with that cell#. In reality isn't it more
likely they just looked at completed phone calls?

As for triangulating the location of a phone by using multiple cells--
even a call in progress--that would require the system to log handshake
negotation info from EVERY cell site--not just the final cellsite# that
"took" the phone but all of them. I'm not saying it isn't possible but
the overhead would be crazy for general practice.

And "a few yards"--if that was possible why'd we need the e911 stuff!!!!

Opinions from the GSM gurus? Is this article full of baloney?
--
Jud
Dallas TX USA

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[POSTED TO alt.cellular.cingular - REPLY ON USENET PLEASE]

In <[email protected]> on Tue, 09 Aug 2005
23:55:17 GMT, Jud Hardcastle <[email protected]> wrote:

>Someone take a look at this article and check me on something.
>
>http://channels.netscape.com/ns/tech/package.jsp?
>name=computing/cpvert/wiredteens
>
>"Unless the power or the wireless antenna is turned off, a mobile phone
>remains in constant contact with the nearest cell towers even when it's
>not being used for a call.

Not constant, but fairly frequent.

>Information processed by the cells can be
>used to precisely locate or track the movements of a phone user."

Not precisely, but roughly, often enough to make a physical search practical.

>"Since a phone is served by several cells at any given time,
>investigators can easily triangulate the location of a device, Errico
>said. In an urban area, where the network of cells is dense and
>overlapping, such tracking can have a margin of error of just a few
>yards."

Not really. Even in E911 Phase II, accuracy is still only 50 to 300 meters.

>Opinions from the GSM gurus? Is this article full of baloney?

Let's just say it's got a good deal of exaggeration.

--
Best regards, HELP FOR CINGULAR GSM & SONY ERICSSON PHONES:
John Navas <http://navasgrp.home.att.net/#Cingular>