UK Mobile Phones (uk.telecom.mobile) Mobile telephone equipment and networks.

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Old January 19th 18, 09:37 AM posted to uk.telecom.mobile
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Default Mobile in Prisons

On 19/01/2018 09:30, Andy Burns wrote:
Martin Brown wrote:

There are devices that can actively block mobile phone
use but they are illegal to use in the UK and HMG can't break the law...


But they can change the law...


Changing the law is always fraught with potential problems.

ISTR that the government isn't allowed to favour itself over others, so
I'd be sure other interested parties would demand that they could do the
same (theatres, schools etc) and then some luddite idiot would demand
that if we have provision to block phones, we should have the ability to
just block certain functions in certain areas (cameras in
playgrounds...) and then some aggrieved fool will start a judicial
review because their pet issue was seen by everyone else as foolish...

And that's all before a prison in an urban area actually enacts this and
the householder who lives next door suddenly loses their mobile signal
annd there's a long article with photos of the entire family (some of
whom have some special circumstances which means they must absolutely
have mobile signal) looking sad in the Daily Mail...

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Old January 19th 18, 09:59 AM posted to uk.telecom.mobile
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Default Mobile in Prisons

On 18/01/2018 18:56, Tweed wrote:

Faraday cages are harder than you might imagine. I’ve used a mobile phone
inside a steel 20 foot shipping container with the doors shut. Go figure...


Indeed. A couple of times recently I've been surprised when somebody got in a lift with me. The lift had apparently metal floor and ceiling and all metal walls. I expected that mobile phones simply wouldn't work in there, but apparently not, as the people carried on chatting as if they were they were in the open air.


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Old January 19th 18, 10:08 AM posted to uk.telecom.mobile
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On 19/01/2018 09:59, Clive Page wrote:
On 18/01/2018 18:56, Tweed wrote:

Faraday cages are harder than you might imagine. I’ve used a mobile phone
inside a steel 20 foot shipping container with the doors shut. Go
figure...


Indeed.* A couple of times recently I've been surprised when somebody
got in a lift with me.* The lift had apparently metal floor and ceiling
and all metal walls.* I expected that mobile phones simply wouldn't work
in there, but apparently not, as the people carried on chatting as if
they were they were in the open air.


To be honest I'm not convinced some of those noise polluters actually
care whether someone is on the other end of the line or not and will
just keep talking.

I seem to remember a comedy show from some years back where an observer
(Ford Prefect from HHGTTG?) came to the conclusion that if a certain
group of people stopped talking, their brains might start working. It
seems apt here.
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Old January 19th 18, 10:10 AM posted to uk.telecom.mobile
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Default Mobile in Prisons

On 19/01/2018 09:30, Andy Burns wrote:
Martin Brown wrote:

There are devices that can actively block mobile phone
use but they are illegal to use in the UK and HMG can't break the law...


But they can change the law...


There are only a handful of scientists and engineers in parliament.
The rest are bean counters, lawyers and worst of all career politicians.

As ever in Britain the law is a complete ass. It is illegal to use them
but *not* illegal to sell them openly to the public:

http://www.cellphonejammers.co.uk/pr...?id_product=46

The same problem arose with CB radio totally trashing the 27MHz radio
controlled model band where people in the UK had paid for licenses.

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Old January 19th 18, 10:13 AM posted to uk.telecom.mobile
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Default Mobile in Prisons

On 19/01/2018 09:59, Clive Page wrote:
On 18/01/2018 18:56, Tweed wrote:

Faraday cages are harder than you might imagine. I’ve used a mobile phone
inside a steel 20 foot shipping container with the doors shut. Go
figure...


Indeed.* A couple of times recently I've been surprised when somebody
got in a lift with me.* The lift had apparently metal floor and ceiling
and all metal walls.* I expected that mobile phones simply wouldn't work
in there, but apparently not, as the people carried on chatting as if
they were they were in the open air.


It doesn't take much of a gap to let signal in.

Serious Faraday cages have beryllium copper strips on the door seal to
make sure that it makes good electrical contact and there are no leaks.
You have to test it from time to time or things deteriorate with wear.

I know a few buildings which are close to de facto Faraday cages in the
deep interior because of their method of construction.

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Martin Brown


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Old January 19th 18, 10:13 AM posted to uk.telecom.mobile
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Default Mobile in Prisons

tim... wrote:


"Graham." wrote in message
...
tim... wrote:


"Chris Green" wrote in message
...
Tweed wrote:

It is constantly reported in the media that there is a problem with
smuggled mobile phones in prisons. Why is it not possible to render
them
useless by a series of pico cells that connect to nothing? A local
cell
with a stronger signal strength is going to capture the mobile. The
pico
cells can emulate all the networks, as it is HMG that is running this
and
they can pass legislation to exempt themselves from spoofing the
genuine
networks. It is often argued that this will affect people nearby but
outside of the prison, but with a suitable number of low power pico
cells
it should be possible tightly define the coverage area. Am I being a
conspiracy theorist in thinking that this is already done, but the
cells
connect to the phone network via an intercept, and are a useful source
of
intelligence?

It's too obviously simple. The powers that be simply don't understand
simple engineering solutions to things like this. Even a Faraday cage
wouldn't be all that difficult surely, when prisoners are outside you
can *see* what they're doing so just screen their rooms and indoor
areas.

Active blocking of mobile signals is illegal

HMG seems incapable of making an exception to that rule for Prisons

passive blocking of mobile signals is unreliable


Before the use of mobile phones was permitted in our local hospital, I'm
sure that they had some sort of gadget that could detect switched on
mobiles. It issued an automated message telling you to turn you phone off.


Surprised by this, but not fundamentally impossible

but given that the "turn you phone off" command isn't enforceable would
probably not be a cost effective solution


I don't know what the range of the gadget was but you would think it could
be used to "sweep" an area for mobile phones or highlight when one was
being used in an area where they weren't permitted.

Always possible I'm misremembering all this of course.

Tim


Perhaps it was a passive system that simply detected RF in the
relevant bands.


then it couldn't send a message telling *you* to turn off


It wasn’t a message directed to your phone, it was just a loudspeaker on
the box on the wall.

Tim



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Old January 19th 18, 10:24 AM posted to uk.telecom.mobile
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On 19/01/2018 09:08, tim... wrote:
Surprised by this, but not fundamentally impossible

but given that the "turn you phone off" command isn't enforceable would
probably not be a cost effective solution


Used to occasionally go into some A&E departments to change their
ambulance radio. We usually carried the "Batphone" which was a
transportable transceiver which could be used to test their set. No one
ever complained about us using it.


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Old January 19th 18, 10:29 AM posted to uk.telecom.mobile
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On 19/01/2018 09:20, Martin Brown wrote:
It is quite difficult to make a reliable Faraday cage that works at
microwave frequencies. There is a pretty good chance that your phone
will still ring when inside your domestic microwave oven.

If HMG were serious about it they would set up a private network of pico
cells in the core of the prison that identified the location of the
phone by triangulation whilst adding enough noise and distortion to keep
them on the line for as long as possible. That way you catch the user
and the phone. There are devices that can actively block mobile phone
use but they are illegal to use in the UK and HMG can't break the law...


A Faraday cage either works or does not work. Needs to be a complete
seal, even the grease from fingers touching the edge of the doors is
enough to let RF in and out. Any mains or telecom cables going out of
the screened area have to be filtered.

Aren't there companies that operate small mobile phone networks inside
places like shopping malls, carrying all mobile phone companies? It
could be that they are doing something like that to identify
unauthorised phones which are then blocked.

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Old January 19th 18, 10:30 AM posted to uk.telecom.mobile
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Default Mobile in Prisons

On 19/01/2018 09:30, Andy Burns wrote:
Martin Brown wrote:

There are devices that can actively block mobile phone
use but they are illegal to use in the UK and HMG can't break the law...


But they can change the law...


Better to do as described on the news. Identify the phone, block it
then get it locked so cannot be used anywhere again even with a
different SIM card.

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Old January 19th 18, 10:35 AM posted to uk.telecom.mobile
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Default Mobile in Prisons

On 19/01/2018 09:59, Clive Page wrote:
On 18/01/2018 18:56, Tweed wrote:

Faraday cages are harder than you might imagine. I’ve used a mobile phone
inside a steel 20 foot shipping container with the doors shut. Go
figure...


Indeed.* A couple of times recently I've been surprised when somebody
got in a lift with me.* The lift had apparently metal floor and ceiling
and all metal walls.* I expected that mobile phones simply wouldn't work
in there, but apparently not, as the people carried on chatting as if
they were they were in the open air.



I have probably written before but Pye wanted a screened room for
testing the Pocketphone so went to see one at the manufacturer's
premises. Someone stayed outside and they spoke to each other on a
Pocketphone.

The manufacturer was surprised so took them to a customer's premises
where they had the top of the range model. Same thing happened and they
could speak from inside to someone at the other side of the factory.

As I mentioned earlier, they found it was the grease from fingers on the
edge of the door and reccommended cleaning regularly with solvent as
well as instructing people to avoid touching that area.




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