Google Answers Logo
View Question
Q: Cell phone tracking ( Answered 5 out of 5 stars,   1 Comment )
Subject: Cell phone tracking
Category: Science > Technology
Asked by: grthumongous-ga
List Price: $10.00
Posted: 31 Dec 2004 16:24 PST
Expires: 30 Jan 2005 16:24 PST
Question ID: 449852
I thought I heard that people could be located by triangulation via
their cell phone.  The context related to employers knowing whether
their on-call staff was really "unavailable".  Is this true?

Request for Question Clarification by pinkfreud-ga on 31 Dec 2004 16:40 PST
Is this the kind of thing you're looking for? If so, I'll be glad to
gather more info about this.

"Mobile phones are about to become aware of their geographic location,
either through receiving signals from Global Positioning System (GPS)
satellites or by triangulation among two or more cellular towers.

This information can guide you to a destination, or can be shared
through the Internet -- with your consent, hopefully -- to show others
where you're located.

Anxious parents will soon turn to a map on a Web page to find Johnny,
who's late coming back from soccer practice, or check on Jane, who's
missed curfew on a Saturday night. Employers will know whether workers
are sitting in a restaurant or moving through a job site.

What's driving the transformation is the federal government's E-911
mandate, which requires cell phones to automatically transmit their
position in emergencies. Wireless carriers have successfully lobbied
to extend several previous deadlines, but it now looks as though the
industry will comply with an order to start universal E-911 by the end
of 2005."

Contra Costa Times

Clarification of Question by grthumongous-ga on 31 Dec 2004 17:15 PST
Yes Pink, this is the right track.

I am aware of a case where a woman was held captive by an ex-husband
and her outgoing call to 911, though brief, was tracked back by police
working with the mobile service provider.  They were able to
triangulate in *near* real-time.  Since she was held in fixed
location, a dwelling house, she was rescued.  That is good and proper
use of the technology, akin to 911 on land-lines that show addresses.

What I am mostly interested in is the privacy breach/security exposure
when anyone who was *ever* provided with one's mobile number could use
technology to determine that you are away from home--miles and miles away.

If it matters, something called "SMS messaging"?? sounds vaguely familiar.
And, if it matters, GSM is the focus.

==> Please Make this a Pink-ga exclusive <==

Request for Question Clarification by pinkfreud-ga on 31 Dec 2004 18:06 PST
I'm unlocking the question because I think it might be best to open
this question to other Researchers. Although I am a whiz with search
engines, I know little about cell phone technology, and I believe
you'll be better served by someone who is more savvy about electronic
Subject: Re: Cell phone tracking
Answered By: hedgie-ga on 01 Jan 2005 01:28 PST
Rated:5 out of 5 stars

what you heard,

  " that people could be located by triangulation"  is true in principle,
but not necessarily a threat to privacy. The important question is who has
access to what data.

Lets' first review the acronym soup associated with cell phones (or mobiles
 as we call them in Europe).

GSM 'global system for mobile' communications is a global standard for mobile
    phones, currently using 900/1800/1900 frequency bands.
     In USA these phones are rare but available, often  called 'world phones'
SIM card is personality module for a GSM mobile, which defines it's identity
(phone number,  operator, and credit arrangements). For privacy
concerns it is good to know that SIMs can be bought two ways, as
prepaid or as subscription cards.
The latter requires that you give the operator your name and address, and often
 a permission to run a credit check. The former is anonymous - same as cash.
SMS  are like e-mail, but limited to 255 characters and sent from
mobile to mobile.
     Like email, they were a spontaneous success, no one planned for:  
 GPS The Global Positioning System can determines position of the
receiver using three nearby satellites.
    Acronym usually refers to use of 24 satellites controlled by U. S.
Department of Defense (DOD), but other countries are developing
similar systems. The idea itself dates back to the Sputnik.
IMEI  - one more acronym -- important for privacy issue :   Each GSM
mobile phone has a unique International Mobile Equipment Identity , a
16 digit number used to identify the mobile phone but not the network
subscriber using the phone.

    This number is embedded into the phone and stays the same when
user changes a SIM, which identifies  the network subscriber using the
phone.  Currently, the number can be changed by an expert, but this
year we are switching to a new system to in which this number will be
indelibly hard-coded in the phone.
    This is done to foil the industry of reselling stolen mobiles,
which is burgeoning in Europe.
  Done with the acronyms, we can now look how it works and what is
revealed when you use a mobile.
   We will skip many details, which can be found here
   and focus on privacy:
   On each call, be it voice or SMS, the IMEI of the mobile is sent to
the operator.
   He (operator is the phone company which sells you their SIM) knows
your position and uses that information e.g. to hand you over to a 
different  tower, as you are moving arond. Each tower has it's cell
(which is why it is called a cell phone) and using three nearby
towers, the operator can and does read your location. Operator does
not know who you are, if you are using a prepaid SIM. These days,
operator usually keep that information for himself
 - but law enforcement can get it, as specified by incresingly less
and  less transparent rules.
   That (operator usually keep that information for himself) is likely
to change, as many services, (emergency, find  nearby restaurant,
hotel, show me way-to ..) can benefit from these data.
 When this data are released,  provider of some such services, will know
 where you are; he will than be able to customize his service.
Provider is gnerally different from the operator - it is a value-added
service - but operator can be a provider of some such services.
    The way it is now, person whom you call, only knows your phone
number, ( caller ID is on by default )unless you block that.
    Of course, large corporation can make private arrangements for
business phones they provide to the employees. Cab operators,
services, .. already do that - mostly using GPS so far, not mobiles.
!!!! However, if you switch OFF your mobil, no one can track you.
 So, one should start worry about the 'Big Brother' when citizens are
ordered to keep their 'mobiles on' - or rather - when the off-switch
will be disabled.
 On the other hand - it may be too late then - may be we should worry now. 
 The trade-off between security and liberty is very real.
 Today, when worms and viruses are migrating from computer networks to
mobile phones, the whole issue is becoming interesting.
    However, it is not the technology, but politics and policies,
which we should worry about first and foemost -but that would be
another great and complicated question.

    Thanks for a great question.

Clarification of Answer by hedgie-ga on 03 Jan 2005 02:55 PST
I want to add that non GSM cells phones, which  do not have a SIMs,
work the same way - just the two sets of information, handset and subscriber
data are not separated, making these phones use less private.

Here is an article about another aspect of the privacy issue:
cell phones with GPS reciever built in:,0,163095.story?coll=la-home-headlines

grthumongous-ga rated this answer:5 out of 5 stars
thanks hedgie.
Wisely, something like the mobile phone equivalent of a "police-band
scanner"  referenced in the following link is *not* sold to the
general public yet(in the USA at least).

lynnm, thanks for your comment.  While the tracking capability is
potentially advantageous for locating family members, who are aware of
the capability and want to be found and aren't located in a GPS
dead-spot, there are of course many potential downsides that
compromise personal security or personal privacy.
As in a 21st century F*tal Attr*ction.  Or a merging of RFID and
GPS-aware mobile phones.

Subject: Re: Cell phone tracking
From: lynnm-ga on 03 Jan 2005 16:45 PST
File this under "coming to a cell phone near you"

I recently participated in a Location Based Services trial with one of
the major cellulat providers in the US. All cellphones currently have
GPS receivers built in however, they are currently only enabled for
emergency use. In the trial we were given phones that had GPS enabled
all of the time and applications to use them. The apps included ones
that are similar to the navigation system in a car. I found these to
be way inferior to the car based systems. Screen size is a big issue
as is the fact that the system in a car has all of the data that it
needs while the phone has to download it and try to keep up.

We also had a phone that acted as a tag. Using an app I could contact
the tag and get realtime information about its location and the
direction and speed that it was moving at. It also had something like
a compass dial and distance indicator. Imagine your family at the
amusement park you have this phone and tags on your kids. Using only
the phone you could track and find them quickly and reliably. When
deployed, the tag is intended to be small enough to put into a pocket
or worn.

Important Disclaimer: Answers and comments provided on Google Answers are general information, and are not intended to substitute for informed professional medical, psychiatric, psychological, tax, legal, investment, accounting, or other professional advice. Google does not endorse, and expressly disclaims liability for any product, manufacturer, distributor, service or service provider mentioned or any opinion expressed in answers or comments. Please read carefully the Google Answers Terms of Service.

If you feel that you have found inappropriate content, please let us know by emailing us at with the question ID listed above. Thank you.
Search Google Answers for
Google Answers  

Google Home - Answers FAQ - Terms of Service - Privacy Policy