"Cell phones are constantly communicating
     with base stations even when you are not
     talking."

"Autonomous Registration" in my market (IS-136, TDMA)
is currently set to every 10 minutes. It was that way
when I was still with ATTWS in '96. This is verifiable
by placing an RF detector (or simply an AM radio) next
to an idle phone and taking note the clicks or RF
indication.

Re-registration also takes place when you move
from your present cell -the phone will take a
look at new candidate control channels, find
a suitable candidate, then attempt a registration
letting the MTSO (the 'switch' or HLR) know what
cell you're now in.

There is also power-up and power-down registrations
as well ...


Jim


----- Original Message -----
From: "Don Hyde" <DonH@AXONN.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Thursday, September 13, 2001 4:14 PM
Subject: Re: [OT]:cell phone locating


> The cell phone industry is currently fighting with the FCC over "E911",
> which would add extra equipment to either cell phone base stations or the
> cell phone handsets or both, which would make it possible to locate a cell
> phone making a 911 call.
>
> There are technical and economic problems i.e. getting it to work and
paying
> for it, but underlying all the fighting is the fear that it would work all
> the time.  Cell phones are constantly communicating with base stations
even
> when you are not talking.  That's how the network knows how to find your
> cellphone for an incoming call.
>
> If it works all the time, then there is a permanent subpoena-able record
of
> your every movement whenever you had your cell phone turned on.  Bad guys
> might hack the system and be able to track you.  Divorce attorneys would
> certainly subpoena such records.  Business rival's attorneys might cook up
a
> lawsuit so that they could subpoena such records.  It could be a great
boon
> for stalkers, assassins and papparazzi, as well as burglars.
>
> Federal courts have already ruled that the FBI could collect such data
> without a search warrant, since it would not involve entering anyone's
home,
> and would be legally treated as 'traffic analysis' which does not
constitute
> a phone tap.  It would require only a single blanket court order to
monitor
> all phones in the country.
>
> Could such a system help police find some bad guys?  Sure.  Bad guys would
> also be able to find all of us, too.  Don't forget that some of the police
> are bad guys, or are in the pay of bad guys.  That's why we have search
> warrants and Miranda and such.
>

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