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Comment by gazrogers | Hacker News Reader

Wouldn't it make more sense to make prisons mobile signal dead-zones?

I believe there was an issue with guards needing to be able to use their mobile phones in an emergency. The majority of the Prison service use TETRA radios now which can be linked in to the rest of the UK mainland emergency services so it shouldn't be an issue but there seemed to be a lot of reluctance so that there was a backup in the event everything else failed.

The people I know who work in prisons in the US aren't allowed to take their phones in. At least here the guards wouldn't have phones to use in an emergency.

I think that TETRA are very similar to GSM phones, in both the technology and the frequencies. So it would probably be hard to avoid any jammers interfering with them.

Yeah or just track all calls from inside the prison and build a map of who the criminals are talking to good source of intel.

SOCA obviously needs to get away from the cop on the beat mentality and think outside the box.

And stoping the rip of charges for inmates using the legitimate phone inside the prisons would stop the use of phone cards as an internal currency.

At night the guards occasionally walk around with some sort of signal detector, so something like this already happens. Don't think they can intercept, but they can tell who's using a phone.

In the US its not allowed in most states to do that, some however our looking into it, what is the law like in the UK?

Great article about the problem in US prisons and how the FTC and mobile carriers don't want the bans against blocking removed. http://www.nytimes.com/2011/01/03/us/03prisoners.html?pagewa...

It's a tricky one, legally running jammers in the UK is a no-no on the books (http://stakeholders.ofcom.org.uk/enforcement/spectrum-enforc...), however I'm not sure whether there's an exemption clause for prisons, or whether you can apply for a license for a jammer for specific circumstances.

So if jammers are out of the question, what about detectors?

Guards generally carry phones on them as well so there'll be quite a few false positives.

Isn't it possible to separate the trafic? I'm not versed in the GSM standard, but there must be some form of authentication. It might be possible to recognize to whom the signal belongs. (In the worst case, cooperation of the cell service providers could be mandated by law in the network cells covering the prison premises.)

I don't think so, or at least non-trivially anyway. Same reason jammers are prohibited as they have a potential spillover, as you can't definitively say 'this is the range it'll work in'.

On the part of service providers also monitoring it it's difficult, a fair few prisons are actually within reasonably populated areas so it'd have to be pretty accurate signal tracking so you didn't get some spillover.

I can't speak to the UK, but in the US jammers are illegal with an explicit exemption for prisons.

or just insist that the prisoners use orange or ee as it is now.

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