Re: Mobile phone tracking, pagers, etc

[Steve Schear <schear@lvcm.com>]

>On Thu, Sep 17, 1998 at 11:56:02AM -0700, Matthew James Gering wrote:
>	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.

If you can get hold of the older, analog, 'transportable' cell phones (like
Motorola used to make) which have an antenna connector, its relatively easy
to spoof the cell ranging system.  Just connect a directional antenna
(<$75) to the port (corner reflectors which have excellent front-to-back
ratios are particularly good).  You should easily be able to fool their
signal strength based equipment into thinking your in an adjacent cell.  If
you can find high ground so much the better.

>
>
>>
>>
>	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.

Universal, an early U.S. analog cellular mfg. built this sort of unit in
the early '90s.  It was an idea ahead of its time.

>> 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....

Yhis is a great cypherpunk service.  Allow our fellows to make free local,
VoIP, calls from our PC/PSTN links.

--Steve

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