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Prisoners' 'innovative' anti-IMSI catcher defence was ... er, tinfoil

PTW
Mushroom

Ready for the down votes, but...

Isn't it about time Ofcom arrived in the 21st century and licensed low powered jammers?

Prisons - problem solved

Theaters - problem solved

Cinemas - problem solved

Quite coach - problem solved

FFS Ofcom!

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Re: Ready for the down votes, but...

On the face of it I don't see an issue... Except maybe in the *quiet* coach where use of a mobile hotspot would still be required.

Also need to be sure that hotels etc didn't abuse this to force guests onto expensive WiFi networks.

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Re: Ready for the down votes, but...

Agree about the coach, lets say I'm driving down the motorway and I cut up a coach and brake check them, I'm going to be really annoyed if it interrupts my phonecall !!!

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Screw downvotes

It's prison, there is no justification for functioning mobile phones. Guards have their radios, prisoners have a wall phone in the dedicated area they can get to when they're authorized to. Blanket the area with jamming, no reason not to. No rights are being infringed thanks to the presence of the wall phones.

As for theaters/cinemas, I'd agree but apparently there, there is a question of rights, namely the right to annoy everyone with a phone complaining about how much it costs to be there trumps the right to benefit from the play/film you paid the same bloody amount to see in peace.

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Re: Screw downvotes

If all prisons were miles out in the sticks then maybe jammers would be OK. But in Britain they're mostly surrounded by legitimately mobile-phone using neighbours, who probably wouldn't appreciate being returned to 20th century comms. IMSI catchers seem to be a more proportionate way of tackling the problem.

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Re: Screw downvotes

One of the legitimate concerns raised seems to be about overspill of the jamming interference beyond the area where jamming is required and may be justified. Surely some sort of variant along the lines of sophon-free rooms from Liu Cixin's Death's End would be a better solution with the risk of electrocution for the careless being simply a serendipitous side benefit?

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FIA

Re: Screw downvotes

But in Britain they're mostly surrounded by legitimately mobile-phone using neighbours, who probably wouldn't appreciate being returned to 20th century comms. IMSI catchers seem to be a more proportionate way of tackling the problem.

Not sure I'd be any more happy about having my mobile usage monitored simply because I lived near a prison. Especially if my IMEI then became flagged as 'used by criminals' as a side effect. I'm sure that'd never cause me problems further down the line...

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Anonymous Coward

Re: Screw downvotes

Why not use RF monitors? A bit of triangulation and then every time a mobile phone (including just for wifi) is used an alert is raised and the location pinpointed.

A decent UNI student could knock a system up as a work experience project.

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Anonymous Coward

Re: Screw downvotes

In regard to theaters, as a primary carer for my dad I'd be unable to go to the theater if my phone was blocked as his personal alarm calls me if he has a fall or needs urgent help.

Minor thing but personally think it's more an issue of cinema staff not wanting to chuck customers out who use their phones.

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Anonymous Coward

Re: Ready for the down votes, but...

First of all, most catchers can be very good and very precise jammers. They use a virtually identical hardware and software - a small cell (aka femtocell). You just re-configure it to give a permanent reject. There is even a code which shuts down a phone so hard you need to do a hard reset on it (though in the past some manufacturers failed that test as it is not mandatory in the 3GPP spec).

The whole affair is the usual "We will not tell you the real reason".

The real reason is different - up to 3G the network authenticates the phone, but the phone DOES NOT authenticate the network. In 4G the phone will authenticate its home network - it is a 2 way auth if memory serves me right (if the operator has enabled it). As a result, the bog standard IMSI catchers stop working - you can evade them by limiting your phone to 4G only. The catcher now needs to be authorized by the operator and in some cases actively talk to the operator backend systems.

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Facepalm

Re: Ready for the down votes, but...

"Isn't it about time Ofcom arrived in the 21st century and licensed low powered jammers?"

Yeah sure that'll work, because everyone knows you can make radio waves stop at a specific distance without having to resort to any sort of metal shielding....

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Re: Ready for the down votes, but...

"Yeah sure that'll work, because everyone knows you can make radio waves stop at a specific distance without having to resort to any sort of metal shielding."

A valid point however realistically I dont think it a major issue.

Ok we have prisons with homes build basically right up to the fence in some areas (Norwich for examle) and in some cases we might not be able to implement this, however for the majority of prisons not in built up areas a few low powered jammers dotted around the prison buildings would suffice.

Of course, the real way to tackle this would be to stop the phones getting there in the first place... but thats probably harder to achieve.

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Thumb Down

Re: Ready for the down votes, but...

Isn't it about time Ofcom arrived in the 21st century and licensed low powered jammers?

Such a shame if you need an ambulance in a hurry. Can you estimate how many lives per year your proposal would cost?

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Meh

Re: Screw downvotes

IMSI catchers seem to be a more proportionate way of tackling the problem.

It's a dead end. The best they can hope for with IMSI catchers is to shift inmates towards other radio technologies. After all, a prisoner just needs some form of short range radio link to a telephone connection or confederate just outside of the jail perimeter. But if the authorities really can't control contraband entering prisons, then what are they going to do about the drugs and weapons that must be flowing in too.

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PTW
WTF?

Re: Ready for the down votes, but...

OK I'll bite...

If only metal shielding stops radio waves can you explain the tremendous amount of Wi-Fi extenders/repeaters on sale?

Prisons tend to have very thick walls and very small windows.

My home femtocell can't get 20 yards past my 9" cavity wall.

Do you really think I would suggest it was done without a site survey!? And 80% coverage means you only need to check the other 20% of cells reducing the burden on staff.

But hey it's only a tech site so let us go with, "I can't see it working so there can be no possible way to implement it!" How very inventive and open minded.

FYI - There were some cheap illegally imported Chinese jammers 10 years ago with a line of site radius of about a 20 yards.

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PTW
Childcatcher

Re: Ambulance

I think prisons have fixed lines, just a guess. You know the world did function prior to the introduction of the mobile phone. And you're about one step from "Think of the children!"

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Re: Ambulance

I think prisons have fixed lines, just a guess.

Prisons have fixed lines and the price per minute is in the pounds range (in addition to them being spied upon even if you decide to call your lawyer or MP).

So this is as less about control (so that the mafia boss cannot run his family out of jail) and more about revenue assurance. End of the day - for each mafia boss in jail there are 2000+ petty criminals which should pay their fair share to whoever HMP has a revenue sharing agreement with.

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Re: Ready for the down votes, but...

You probably shouldn't be reliant on mobile phone technology for ambulance calls anyway, especially in the house.

Am I the only person who has a good old fashioned powered-from-the-network plugin phone for emergencies?

(we need a luddite icon)

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Coat

Re: Ready for the down votes, but...

Isn't it about time Ofcom arrived in the 21st century and licensed low powered jammers?

Wot?! They are - not licensed? I praise my quite, babble-free commute on the train.

Mine's the one with the jammer in its pocket

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Re: Ready for the down votes, but...

Seeing as how government seems to think everyone's a criminal anyway, any proposal that would result in more of them dying would be embraced by the powers that be. Its just that pesky problem of keeping enough of us around to keep the tax money coming in that prevents them from having the lot of us killed off in the name of preventing thought crimes.

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Re: Ready for the down votes, but...

Jamming wifi is already covered - the FCC has bared its fangs a few times, but Ofcom is the kind of regulator who avoid doing anything.

Theatres and others can be locked down fairly easily. I know of one multiplex that was built with RF in mind from the outset (the owner was a movie enthusiast and pissed off about yammerers) and phones simply don't work once you go into the threatres. No jammers needed.

As far as IMSI or not IMSI is concerned: It's actually better to build genuine mobile cells at or close to the prisons and then have them lockout call access to anything within N metres of the antennas in the directions matching the location of the prison (It's perfectly feasible to lockout where distance is greater than N and less than M too, or direct them to an authorised tapping system)

The problem witch cracking down on mobiles in jails is that it's worth bearing in mind that the vast majority of smuggled phones in the UK are used to keep in contact with family, due to over-restrictive access to and overly high pricing for the in-prison phones, not for other ongoing criminal shit.

Isolated lags end up with higher recidivism rates upon release and lack of family contact is also linked to higher in-prison violence levels so this genuinely needs addressing as a matter of high priority - at which point anything left inside the walls should be more nefarious and able to be stomped on hard. The whole "retribution/revenge" vs "reconciliation/repair" thing needs to be sorted out because you don't really want a revolving door where going to prison turns people into hardened crooks who will only ever know prison or a crminal life outside. The IMSI stuff is only tackling one part of a hugely complicated mess.

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Re: Screw downvotes

"Minor thing but personally think it's more an issue of cinema staff not wanting to chuck customers out who use their phones."

I've been to movies where someone in the audience has continued a very loud, very long converation for 30+ minutes whilst a movie's running.

If your'e a carer and you're on a break then someone needs to take over the responsibliity. Being on 24*7*365 duty is unfair on everyone.

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Re: Ambulance

I think prisons have fixed lines, just a guess. You know the world did function prior to the introduction of the mobile phone.

The OP listed more places than just prison. And you picked the only one where it would be expected not to have mobile phone coverage or where use would be prohibited even if turned silent.

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Re: Ready for the down votes, but...

"a few low powered jammers dotted around the prison buildings would suffice."

Based on my limited knowledge and experience, the answer is no, that will not suffice.

NZ Corrections has some barmy contract for some private company to block mobile signals. Original budget was 20 million plus a million a year to run it. Currently cost ~2 billion, and is about 95% effective (at the cost of ruining mobile around prison sites), meaning that almost all confiscated phones fall into the 5% of phone+sim combinations that work. There are also often spots where you can get a clear signal which are not apparent in a site survey, but are to lags who have a lot of time on their hands.

Having the telecoms company trace and log/block phones was the more sensible and realistic option, but wasn't done as it would have had a higher running cost.

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Stop

Re: Ambulance

I think prisons have fixed lines, just a guess. You know the world did function prior to the introduction of the mobile phone. And you're about one step from "Think of the children!"

I don't know what the figures are now, but in August 2004, 29% of emergency calls to ambulances in central London were by mobile phone (http://publishing.rcseng.ac.uk/doi/pdf/10.1308/003588408X242079).

And the odds of dying at the scene when the incident is called in by mobile phone are only 77% of the odds of dying at the scene if the call is made on a landline (https://www.ncbi.nlm.nih.gov/pubmed/22142669). Even if the world did function prior to the introduction of the mobile phone, and indeed the steam engine and the wheel, mobile phones are now critical life saving aids and widely restricting their ability to call the emergency services would certainly result in many needless deaths.

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Re: Ambulance

You're missing the point - the fixed line ensures an ambulance can be called, regardless of jamming. Non-emergency phone cost is a different issue (and should be regulated to the same price as public phone boxes).

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Re: Screw downvotes

You are obviously not a parent.

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Re: Ready for the down votes, but...

"Am I the only person who has a good old fashioned powered-from-the-network plugin phone for emergencies?"

Nope. I have one in the cupboard right by the wall socket. Ready in case of power cuts / etc. We care for two elderly parents and may need medical aid at any time. It's not being a luddite - it's being sensible.

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Re: Screw downvotes

"If your'e a carer and you're on a break then someone needs to take over the responsibliity. Being on 24*7*365 duty is unfair on everyone."

You clearly don't have any experience of being a carer in Britain today with the almost total lack of state help once caring for somebody becomes your responsibility. You are expected to be on duty 27*7*365, and the rest. Once we battled through the red tape and managed to get some minor respite care we are still needed to be available as the only staff offered by care companies are unable to handle any emergencies.

And yes, I agree, it is unfair. But what else do you do? Put them in a care home? Have you read reviews and reports of them? Unless you're offering to help some carers out by taking some of the "unfair" burden then simply don't comment on it.

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Re: Screw downvotes

I don't usually complain as my views don't usually flow with the majority here but who the heck actually down-voted my points on in home care? I'd love to see your justification....

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Re: Ready for the down votes, but...

Alan Brown writes: "It's actually better to build genuine mobile cells at or close to the prisons and then have them lockout call access to anything within N metres of the antennas in the directions matching the location of the prison (It's perfectly feasible to lockout where distance is greater than N and less than M too, or direct them to an authorised tapping system)"

So the simplest way would actually be to put the cell towers right in the middle of the prison, and lock out anything closer than the radius?

Disturbing the neighbours is easily avoidable by having all prisons be circular; it's the most efficient layout for a panopticon anyway.

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Porridge 2017 Script

Mr. Mackay: Fletcher! What's that large rectangle of tin-foil doing on your wall?

Norman Stanley Fletcher: Oh that, Mr. Mackay; it's a poster.

Mr. Mackay: It looks just like a large piece of tin-foil to me.

Norman Stanley Fletcher: Not at all Mr. Mackay; it's modern art; it's meant to help me reflect on my misguided ways...

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Re: Porridge 2017 Script

I can't read that without hearing the voices of Ronnie Barker and Fulton MacKay !

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Re: Porridge 2017 Script

I will step into the soylent green processing tank on the day when I can no longer hear the voices of Ronnie Barker and Fulton Mackay.

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Anonymous Coward

Re: Porridge 2017 Script

"I can't read that without hearing the voices of Ronnie Barker and Fulton MacKay !"

That's okay, I'm sure they'll do it with Ricky Gervais and Jack Whitehall. Imagine it in their voices instead.

Oh... I've spoiled it for you. Sorry!

Ain't I a stinker? (^_^)

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Correction

"They are used extensively in the US, where law enforcement agencies must apply for a court warrant to use them." should read:

They are used extensively in the US, where law enforcement agencies are theoretically supposed to apply for a court warrant to use them but generally use them whenever they want to.

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Screw(s) up

I don't know if I should congratulate the lags or laugh at the screws.

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Anonymous Coward

Re: Screw(s) up

Call me a cynic but if I had to implement a solution like this I'd gently publicise a fictitious, simple way round it to stop people trying to find a more effective method.

This scheme will work best if people believe it isn't working at all.

As for blocking mobile phone use, well, that's probably less useful than monitoring it.

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Two questions:

Where did they get tin foil from such that they could all use it to block their signals from their own cells?

How do the mobile phones they have smuggled in get charged?

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"...How do the mobile phones they have smuggled in get charged?.."

Nokia 3310. Lasts for the entire duration of their stay... ;)

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Anonymous Coward

They don't use the new fangled phones that last a day, they use the good old fashioned types that last weeks without charge. But when they do need charging, they pull the charging cable out of their arse, plug it into the phone and put 2 fingers in a wall socket.

Anonymous as I don't want to be found out :)

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I'm going out on a limb here, but I guess they get the foil from the kitchen.

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Anonymous Coward

Having had the misfortune to deal with prison officers I can say with a fair degree of confidence that the majority of these phone, drug and availability of tinfoil problems are down to corrupt prison officers.

The bruises have faded away, the memory has not.

There are some evil corrupt bastards in every profession, the prison service has more than its fair share.

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"There are some evil corrupt bastards . ."

Aren't you being a bit harsh on a very well meaning body of men?

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they get the foil from the kitchen

Sounds more comfortable than smuggling in a mega roll of kitchen foil the same way the phones arrive...

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Where did they get tin foil from such that they could all use it to block their signals from their own cells?

Most likely it had been used as a wrapper for some illicit drugs that had been passed over the wall.

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"Aren't you being a bit harsh on a very well meaning body of men?"

I did in fact hear the prison top dog fella admit that some of his screws were corrupt on the radio the other day, when discussing why some prisoners fear for their lives and "self confine" themselves to their cells

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"Aren't you being a bit harsh on a very well meaning body of men?"

Apparently there aren't as many Porridge fans on here as the earlier posts would suggest.

Have an upvote from me.

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"I'm going out on a limb here, but I guess they get the foil from the kitchen."

So prisoners are walking out of a kitchen with a concealed metal object, back to their cell, where it's stashed, traded and used and nobody notices?

This is exactly my point. There's a problem right there.

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"Porridge fans"

We're obviously getting old and less relevant to the yoof of today.

The line was a bit obscure and UK centric but it was used in many episodes. Thank you for noticing - small victories.

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