From: Chip Mefford <cmefford@video.avwashington.com>
Date: Fri, 18 Sep 1998 07:24:57 +0800
To: Dave Emery <die@pig.die.com>
Subject: Re: Mobile phone tracking, pagers, etc
In-Reply-To: <19980917222329.A1364@die.com>
Message-ID: <Pine.LNX.3.95.980918081019.15546H-100000@video.avwashington.com>
MIME-Version: 1.0
Content-Type: text/plain





Actually, 

there seems to be a screw up out  there.

Right now, one can go down the 7/11, and pay 
cash for a prepaid cellphone, and renew it with 
cellphone time cards also purchased with cash.

No paperwork, NONE.

I have one.

While all of the technology applies, and certainly it is possible
to determine things by analyzing calling habits, I can't see how one
can easily determine who has cellphone #blahblahblahblahblah when 
you just bought a box at an out of town 7/11 during the breakfast
rush with cash.

Esp if one doesn't make a lot of calls.

On Thu, 17 Sep 1998, Dave Emery wrote:

> On Thu, Sep 17, 1998 at 11:56:02AM -0700, Matthew James Gering wrote:
> > 
> > Regarding the tracking of mobile phones, are all current types of phones
> > susceptible?
> > 
> > There was a recent post here regarding tracking of GSM phones.
> > TDMA/CDMA, analog/digital, PCS-band, etc, are they all equally capable
> > of being tracked?
> 
> 	All the wireless standards I am aware of allow for registration
> and polling phones to find out if they are on and available without
> ringing them. This provides silent location information to the nearest
> cell of a phone merely turned on, location  which may be hundreds of
> feet in tightly congested urban areas and tens of square miles in
> suburban and less populated areas.   Some system operators apparently
> use this feature with all active phones to relieve congestion on paging
> channels, while others do not actively track phones not being used
> except in certain situations or parts of the network.   Of course
> location to a cell is always available during a call...
> 
> 	The FCC has mandated that this cell-granularity location
> information be made available to E-911 centers on emergency calls, and
> there may be some situations in which it is currently made available to
> domestic law enforcement under other circumstances, though CALEA
> restricts such availability without warrents.  Whether and under what
> circumstances law enforcement can request a poll be transmitted
> (re-registration) to locate a silent but powered phone is less clear.  
> It would seem that CALEA forbids this, but what in fact is the practice
> by such agencies as the FBI working quietly with cell carriers in places
> such as NYC is less clear.
> 
> 	In the future FCC rules will require that all E-911 calling
> wireless phones be located to 125 meters 67% of the time.  There are
> proposals to do this with differential time of arrival (DTOA)
> or other direction finding techniques (apparently a hard problem
> in cities with lots of multipath propagation due to reflections)
> that work passively on some or all cell calls and registrations
> (thus allowing tracking of everybody), or by cooperation with the
> cellphone handset that could be only turned on when the user wished
> to be located (an E-911 emergency) and disabled otherwise.   One
> version of this would use GPS rather than ranging or other techniques
> to determine position relative to the cell sites.    Of course all
> the user disaablable  techniques such as GPS and DTOA done in the handset
> firmware only will work with future cell firmware and hardware
> and not legacy handsets, and because of this may not be acceptable
> to the FCC.
> 
> 	There are some distinctions between CDMA, GSM, analog and TDMA
> (non GSM), in respects to exactly how easy it is to implement precision
> location meeting the FCC spec passively and on all calls at all times.
> Apparently CDMA with its very tight power control to minimize the near-far
> problem makes it fairly awkward to reliably triangulate position from
> multiple sites since the mobile may be only detectable at one site
> at any time...  What this means in practice is that some wireless
> technologies are more likely to require some definate active firmware
> intervention to do precision location, whilst others may allow it
> with no special intervention.   If the FCC allows this intervention
> to be enabled by a user, this may provide some opportunity for
> location privacy.
> 
> 
> > 
> > However pagers are not, correct? They just broadcast an entire area to
> > page instead of the pager keeping the network informed of their
> > location.
> 
> 	The one way pagers work this way.  The guaranteed delivery two
> way pagers do support registration and will know the location of
> the pager after a page has been sent to it and any time the system
> wants to determine it.   This location will be quite coarse with current
> two way (reFlex) pagers with cell sites some distance apart, but 
> DF techniques are quite possible and could be implemented by law
> enforcement or spooks or other interested groups.  Unlike wireless phones
> there is no current FCC requirement for positioning information distribution
> or precision positioning infrastructure, so two way pagers aren't
> likeyly to be routinely located accurately any time soon.
> 
> 	Of course most modern wireless phones support paging message
> delivery, so more and more people will be using wireless phones with
> the FCC mandated tracking accuracy for paging...
> > 
> > One thing I have long wondered: Why don't they make phones that
> > "wake-up" by a paging signal and then accept the call? It might increase
> > the connect time significantly, but it would also increase the potential
> > stand-by time indefinitely, and the location of the user is only exposed
> > when calls are in progress, not while the phone is on stand-by.
> > 
> 	Wireless phones do currently work this way.  They listen to the
> forward control channel for a paging message that says they have got a
> call coming in and only then do they transmit.  The amount of power used
> in transmitting would quickly use up the battery if they continuously
> broadcast.  The problem with cellphone location is that they can also be
> paged with a registration request that does not cause them to ring
> or show any evidence of transmitting, but sends back a brief message
> burst (not using much battery).   This can be made to happen every
> so often, or only when polled.
> 
> 
> > Are there any paging services (particularly alpha paging) that work on a
> > global scale? You would think daily pager rental service (esp. at
> > airports) would be popular. You could have an email address, even a
> > static phone number, that could re-route messages to any pager that you
> > happen to have at the time (PSTN-IP-PSTN, or even easier if the pager
> > service gives SMTP addresses, which most do these days).
> > 
> 	There are nationwide pager services that broadcast your pages
> over very wide areas or depend on registration to locate you down to
> a smaller area.  But yes, you can get paged anywhere in the US and
> several other countries.  And the new LEO satellite technology will
> allow paging over whole continents or potentially anywhere in the world.
> 
> 
> > Similarly a PSTN-IP-PSTN interface for voice could give you a static
> > phone number that you could dynamically forward anywhere untraceably.
> 
> 	The LEAs don't like this concept, and one of the provisions of
> the CALEA wiretap stuff is providing tracing of calls forwarded so you can't
> do this....
> 
> 
> -- 
> 	Dave Emery N1PRE,  die@die.com  DIE Consulting, Weston, Mass. 
> PGP fingerprint = 2047/4D7B08D1 DE 6E E1 CC 1F 1D 96 E2  5D 27 BD B0 24 88 C3 18
>