In article ,
(Hans K0HB) writes:

Since a
cell phone transmits a signal even when not placing a call, they can
require that the unit be turned off at all times while on the
premises.

It does? Oh, yes, the receiver's Local Oscillator "transmits" a
picayune picoWatt or so...severe QRM to anything within a
couple millimeters distance...

LHA

(Len Over 21) wrote

In article ,
(Hans K0HB) writes:

Since a
cell phone transmits a signal even when not placing a call, they can
require that the unit be turned off at all times while on the
premises.

It does?

Yes, Lenover, it does.

Oh, yes, the receiver's Local Oscillator "transmits" a
picayune picoWatt or so...

And much more than the picayunish oscillator leakage you allude to (if
the receiver is even so crude as to have an actual Local
Oscillator)......

As soon as a cell phone is powered up it immediately establishes radio
communications with the MTSO over the control channel, comparing
SID's, negotiating a registration request, and other similar
housekeeping chores. This radio communications occurs even if you
never actually place an outgoing call or recieve an incoming call.

Sunuvagun!

With all kind wishes,

de Hans, K0HB
--
http://home.earthlink.net/~k0hb

(Hans K0HB) wrote in message . com...
(Len Over 21) wrote

In article ,
(Hans K0HB) writes:

Since a
cell phone transmits a signal even when not placing a call, they can
require that the unit be turned off at all times while on the
premises.

It does?

Yes, Lenover, it does.

To which question do you answer?

Transmitting a signal even when its not placing a call?

Requirement to turn off a -lawfully- allowed RF device?

Hopefully not yes to both.

Oh, yes, the receiver's Local Oscillator "transmits" a
picayune picoWatt or so...

And much more than the picayunish oscillator leakage you allude to (if
the receiver is even so crude as to have an actual Local
Oscillator)......

Instead of the "DX" oscillator?

I've heard of cell site conmfirmation from 27 nm.

Thank goodness cell phones don't require a knowledge of Morse Code.

It would have been a monumental flop.

As soon as a cell phone is powered up it immediately establishes radio
communications with the MTSO over the control channel, comparing
SID's, negotiating a registration request, and other similar
housekeeping chores.

Just relax and call it handshaking.

This radio communications occurs even if you
never actually place an outgoing call or recieve an incoming call.

Doesn't even rate a "duh!"

That's why you find guys at the other end of the tunnel standing by
with computer controlled "law enforcement" scanners logging all the
codes as you pop out the other side and handshake with the local cell
site.

Then they sell them to Taliban operatives and drug dealers.

Sunuvagun!

With all kind wishes,

de Hans, K0HB

Yeh. Dittos

Brian

(Brian) wrote


This radio communications occurs even if you
never actually place an outgoing call or recieve an incoming call.

Doesn't even rate a "duh!"

You know that and I know that, but Lenover didn't even have a clue.

Sunuvagun!

With warmest personal regards,

de Hans, K0HB

On 31 Oct 2003 17:35:18 -0800, Brian wrote:

That's why you find guys at the other end of the tunnel standing by
with computer controlled "law enforcement" scanners logging all the
codes as you pop out the other side and handshake with the local cell
site.

Then they sell them to Taliban operatives and drug dealers.

And they sell then to the guys who sell them to other guys who clone
cellphones which are sold to still other guys who set up curbside
"telephone booths" in immigrant neighborhoods to call relatives in
foreign countries at "discount rates".

At least they did have been doing those things for the last 10 years.

--
73 de K2ASP - Phil Kane

Phil Kane wrote:
On 31 Oct 2003 17:35:18 -0800, Brian wrote:

That's why you find guys at the other end of the tunnel standing by
with computer controlled "law enforcement" scanners logging all the
codes as you pop out the other side and handshake with the local cell
site.

Then they sell them to Taliban operatives and drug dealers.

And they sell then to the guys who sell them to other guys who clone
cellphones which are sold to still other guys who set up curbside
"telephone booths" in immigrant neighborhoods to call relatives in
foreign countries at "discount rates".

At least they did have been doing those things for the last 10 years.

I don't think this happens very often any more, however. All the digital
phone standards I know about (CDMA, TDMA and GSM, I don't know about iDEN)
use encryption, both on the control channel and for the voice payload.
While I've seen academic criticism of the algorithms they use, I don't
think there is a practical way for a guy with a scanner hearing the
signals to crack this. Digital mobile phone service is still secure for
practical purposes.

The cellphone cloners used to get their data from the AMPS control
channel, which was unencrypted, but I'm pretty sure there are no cell
phone companies left which sell exclusively analog phone service (it has
probably been 5 years or more since you could buy an analog-only phone).
AMPS support continues to exist, by FCC mandate, only to support
off-network roaming, which means that pretty much the only AMPS users
you're likely to find are people away from home in rural areas not covered
by their provider's digital service. This is a small enough population
that the reduced opportunities for fraud of this type hardly justify
the cost of the equipment for programming the phones.

I think these days the bulk of cell phone fraud is subscriber fraud,
where service is obtained using someone else's name and personal
information.

Dennis Ferguson

On 4 Nov 2003 21:11:38 GMT, Dennis Ferguson wrote:

I think these days the bulk of cell phone fraud is subscriber fraud,
where service is obtained using someone else's name and personal
information.

That's what my sources tell me.

--
73 de K2ASP - Phil Kane