back to article Scotland to test mobe signals slammer jammer

A pilot scheme to test mobile phone signal blocking technology in Scottish prisons will go live in two jails in the next few weeks, Justice Secretary Kenny MacAskill announced. MacAskill was visiting HMP Shotts, one of the prisons chosen for the pilot, to see the technology beings installed and said that the scheme was due to …


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  1. Ol'Peculier


    Can this be extended to theatres and cinemas please?

    1. Khaptain Silver badge

      Re: Rollout?

      And public transport.

    2. Anonymous Coward
      Anonymous Coward

      Re: Rollout?

      Can this be extended to theatres and cinemas please?

      A cheapo portable jammer will do you fine :)

    3. Alan Brown Silver badge

      Re: Rollout?

      Theatres and cinemas are enclosed spaces which can be quite effectively blacked out using metallic paint on the walls and possibly a very low power jammer (illegal now, but suspected to be in use some places)

      Prisons aren't. The neighbours of Mt Eden prison in Auckland NZ aren't particularly happy that they can't use mobiles within about 200 metres of the prison boundary (suburban housing srruounds the prison on all sides), thanks to jamming systems in use there

  2. Bogle

    Behind bars

    Surely we could just upgrade the buildings with giant Faraday Cages?

    1. Mark #255

      Re: Faraday Cages

      No, we couldn't.

      Faraday Cages are a static/low frequency concept; as you get higher in frequency, the doors/windows/riveted seams let through more and more energy.

      EM screened/anechoic chambers (which do block mobile phone/wifi/etc signals) are really hard to make, and really quite expensive (5 to 6-figure sums) because of it. They're also easy to compromise, either deliberately or accidentally*.

      * Yesterday, I had breakthrough into my chamber at 1.8 GHz; it transpired that one of the (sodding expensive) coax cables had degraded.

      1. Dave Harvey

        Re: Faraday Cages

        Perhaps they should get advice from Virgin Trains - they managed to figure how to make large Faraday cages effective at mobile frequencies (aka their carriages) many years ago!

    2. This post has been deleted by its author

  3. Bogle

    Signal strength

    So there'll be no bars in these prisons, eh?

    Mine's the one with the suppository sized Nokia 100 in the pocket ... ouch.

    1. TRT Silver badge

      Re: Signal strength

      I don't fancy the idea of some prison officer fiddling with my hand-held, thank you.

    2. Euripides Pants Silver badge

      Re: Signal strength

      There better not be any bars in prisons! Convicted criminals should not be able to drown their sorrows with alcohol.

      Mine's the one with the sterno in the pocket

  4. Barrie Shepherd

    I would have thought that a credible solution would be for the mobile carriers to install a base station in the prison (with Tx's serving each carrier) and for the carriers equipment to advise the prison authorities when a phone within the cell coverage was in use. This would allow more phones to be detected.

    Carriers should also be able to arrange for calls from mobiles via the cell to be blocked from connection to the PSTN or just rerouted to the NAS/GCHQ :-)

    A white list would allow official Warders phone through.

    1. Dale 3


      That wouldn't stop someone from going into their phone menu and manually choosing to connect to a different network.

      1. Barrie Shepherd

        Re: Microcell

        All Networks would have a presence on the box.

        1. Anonymous Coward
          Anonymous Coward

          Re: Microcell

          @ Barrie Shepherd

          I used to work for a company that made products that did exactly that. And more besides.

    2. Phil O'Sophical Silver badge

      If such a base station were in the prison there's a good chance that there would be screened areas where the outside main-network base stations had stronger signals and were preferred by the phone. You could probably bulld some suitable screening equipment to create such areas. Making the fake base station signal strong enough to guarantee that all phones inside used it, while preventing phones from outside seeing it, would be challenging, so say the least.

    3. JetSetJim Silver badge

      even easier

      Operators are currently playing with tech to geolocate every call in the network. just run an analysis, list all IMSIs that made calls from that area and put those that make calls in the prison on a blacklist that all operators share. could do some other tests to see if those numbers make any calls elsewhere too. or check the subscription address. lots of other things you could do to gain confidence in the decision to mitigate false positive chances.

      this would not require installation of extra masts, either

    4. Anonymous Coward
      Anonymous Coward


      an 600 quid Ettus USRP software defined radio running OpenBTS will either passively record all TIMSIs (& metadata) or should you go active (with the appropriate licenses) on GSM then you can wireshark *everything* including call/data content. call it a grand with a few SMA connectors, antennas and a crappy laptop with a big hard-disk.

      might as well offer 'free' (canadian NSA style 'free') WiFi prisoner access at the same time with an DD-WRT enhanced AP, for added (meta)data-slurping.

    5. Nifty

      Which is more or less what I said in this thread

  5. fajensen Silver badge

    There is a patent for that (probably granted because this is quite easy to do, so lawyers can make some beer money from the inevitable dispute).

    The patent is owned by Telenord: One configurer one or more base stations as needed, which one controls, so that they provide good coverage of the protected area. Mobile phones within coverage will then roam to one's base stations, when they do, issue a command via GSM to switch them off (there is a reason a mobile phone is called a "terminal" in GSM-speak, a mobile is really a dumb, passive, device)

    1. Barrie Shepherd

      ....configurer one or more base stations as needed, which one controls, so that they provide good coverage of the protected area.

      This would require the operator to hold a license for the spectrum - which is owned by the carriers who would not be keen on releasing spectrum for the purpose of a company blocking their signals.

      If there was suitable spectrum then a GSM in a box installation like would suffice.

  6. Mookster
    Black Helicopters

    Not very Ambitious

    Wouldn't it be easier just to deploy one of those fake base-stations? They could then listen in...

  7. Pete 2 Silver badge

    Listen in

    > prison staff to interfere with the wireless signal in their jails

    Surely a better solution would be to either eavesdrop on the calls or to trace the numbers being called?

    That way the authorities could get a handle on any crimes that were being planned or committed via phone and maybe haul in the inmates' outside contacts, too?

    It may be that the prison personnel don't even need to listen in (or trace the phone numbers) if they can credibly "sell" the story that they are doing that?

    1. Khaptain Silver badge

      Re: Listen in

      The GCHQ and the NSA don't seem to have a problem recording non-criminal conversations, I can only presume that also include the criminal conversations and obviouslly share the info with the local plods.

      1. Anonymous Coward
        Black Helicopters

        Re: Listen in

        "The GCHQ and the NSA don't seem to have a problem recording non-criminal conversations, I can only presume that also include the criminal conversations and obviouslly share the info with the local plods."

        Which (whilst acknowledging Hanlon's Razor) actually raises an interesting point - if GCHQ can listen in on calls as a matter of course, there'd be no need for honeypot-style base stations at the prison, just the normal network infrastructure. It's reasonable to assume that intelligence gathering from illicit phone calls would be more advantageous (potentially a goldmine in fact) than prevention of calls.

        I leave you to entertain your wildest conspiracy theories as to what that might mean for actual GCHQ/NSA capabilities - or (just for fun) a double-bluff regarding their lack thereof...

  8. Havin_it

    This ought to be unnecessary

    ...if we could just solve the overriding problem of the bloody things (and all manner of other contraband) getting inside in the first place, which has to be mainly down to corrupt screws turning a blind eye (or being too understaffed to keep a proper eye on whose hands are under the table at visits).

    1. Annihilator

      Re: This ought to be unnecessary

      That's the equivalent of refusing any sort of antivirus because you have a good firewall.

    2. Anonymous Coward
      Anonymous Coward

      Re: This ought to be unnecessary

      I live fairly near Nottingham Prison and know some prison guards, the phones were mainly getting in by putting them in long socks, possibly with padding, then flingling them over the wall in the hopeful vicinity of the excercise yard. Yes, the screws looked for these, but I got the impression it was like catching snowflakes - some always got through.

      I leave the comparisons of a rain of filled socks to snowflakes to someone else.

  9. Christoph Silver badge

    Are the phones really that difficult to trace?

    The US can track down mobiles in Afghanistan closely enough that they can send robots to kill anyone who has committed the capital crime of happening to be near them. Are prisons that much more difficult?

    1. Anonymous Coward
      Anonymous Coward

      Re: Are the phones really that difficult to trace?

      Hey, good point. Just have them send a drone when they detect a signal in the courtyard :)

  10. Ross K


    Somebody running a criminal enterprise, ordering contraband or putting the frighteners on a witness can accomplish his goal just as easily by having a word with a "colleague" at visiting time.

    Mobile phones aren't needed.

    A couple of reasons why prisoners use mobiles:

    Speaking with family members, as they know that calls made from a prison pin phone are monitored by staff and/or police. Rightly or wrongly, they don't want their family business overheard and archived for later use.

    Prison being prison, everyone is supposed to have x amount of time on the pin phone. If you're unable to assert yourself you might find that you don't get to use the phone.

  11. Wilseus

    Despite it being a criminal offence to take a mobile phone into a prison (even an officer can be sacked for doing so) the prison authorities are surprisingly lax with enforcing this. I know this because my ex who was a prison officer, used a mobile phone detector (yes, they exist) to scan the landings one night when she was bored. She found several cells that night with mobile phones being used, yet they didn't have a member of staff doing this as a matter of course.

  12. dervheid

    As the Kaiser Chiefs once sang...

    " I pred...

    (stuck in your head now...)

  13. Velv Silver badge

    Surely the simplest option is to lace the prisoners food with Picolax - that would prevent the, er, storing of mobile phones.

  14. michael cadoux

    Yes, let's get something useful from GCHQ's expertise! Plus issue warders with scanners.

  15. JaitcH

    The ministry is in the midst of spending £70,000 on a research project to figure out ...

    how prisoners are using their illegal mobes in English and Welsh jails.

    QUESTION: Why not just call GCHQ?

  16. Roger Stenning
    Thumb Down

    It's a good idea, but...

    ...the laws of physics being what they are, there's no way that they can assure us that any jamming signal they broadcast will remain within the walls of the clink in question.

    There will inevitably be leakage, and people who are merely walking or driving past any nick using this system in a built up area (can you say Brixton, Holloway, or even Wormwood Scrubs, just to name a few in London) will be affected by this system - this is especially worrying, as any of those people may be calling the emergency services for some reason when they get hit by the leaked jamming signal.

    Any cellular jamming system used therefore, must be installed in a building that can be completely shielded (Faraday Cage, as mentioned above) so as to prevent such leakage. And for a prison, the costs are just too prohibitive to retrofit each building with such a cage.

    There has to be something done, obviously, but a blanket jamming signal is NOT the way to do it.

    1. Androgynous Cupboard Silver badge

      Re: It's a good idea, but...

      And that's not how it's done. I know someone that does this (in NZ) and the process involves many small devices positioned around the site, which have their strength/position adjusted so that they're blocking just enough and not interfering with the area outside the prison. That's the theory, anyway.

  17. Anonymous Coward
    Anonymous Coward

    It can be done.......

    The blocking of mobile networks in prisons is possible, some googling found this:

    Might cost a bit though!

  18. pacman7de

    Shhh: Society for Handheld Hushing

    `After reading a story in the NYT, Jim's wife Heidi came up with a method to fight back against the obnoxious cell phone users that we all have to deal with in stores, restaurants, trains and pretty much everywhere else. Can design ride to the rescue? Jim and the incomparable Aaron Draplin think it can. So, as a public service, we introduce the reasonably polite SHHH, the Society for HandHeld Hushing'.

  19. goldcd

    Surely 'blocking' is a bit of a sledgehammer?

    It's already possible to get a rough fix on the co-ordinates of a phone. Why not ask the providers to indicate which phones seem to be in, and stay in, prisons?

  20. Anonymous Coward
    Anonymous Coward

    Cell phones?

    Prisoners have telephones in their cells?


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