Why Corrections have got it all wrong jamming cellphones.

By Steve Biddle, in , posted: 23-Aug-2007 10:52

So corrections want to install cellphone jammers in prisons to stop prisoners making calls? This is an issue I spent some time discussing yesterday afternoon with a friend who had done some brief work on cellphone jamming in NZ a while back when corrections first proposed installing equipment into prisons. The technology can work in some circumstances but can also prove unreliable. What it doesn't deal with however is the issue of blocking WiFi signals. With the number of cellphones now with VoIP and WiFi capabilities the move by corrections to install cellphone jamming equipment is going to about as effective as giving somebody a two roadcones to block a road. It will stop some people but anybody who has a brain (ie many prisoners) will realise an exploit to get around the system is dead easy.

Firstly smuggle your WiFi/VoIP capable Nokia phone or Netgear Skype phone into a prison (very easy). Next your mate parks outside with a WiFi AP hooked up to a cellphone (again very easy) and before you know it you're connected to the real world again. Simple isn't it. I wonder why not a single person at corrections was aware of such an exploit? They're going to waste $5 million of taxpayers money on a system that will have exploits from day one.

It reminds me of their stupid system about 10 years ago were prisoners were only able to dial fixed nominated numbers from the prison payphones. They would nominate friend X on number 1234567 and were free to call them. Corrections spent a lot of money implimenting this rock solid system to discover that some smart people realised if you rang your nominated mate he could put his phone on divert to another number and talk to anybody they wanted.

Bruce over at Aarkvark has also posted about the issue of cellphones in prison and has a few comments  in regards to it.

Other related posts:
Why a 24hr parking limit won’t fix the Wellington airport parking issue.
CCTV exposed. Why understanding network security is so important.
Anker make some of the best USB chargers and powerbanks available. Now you can get their products shipped directly to New Zealand

Comment by chiefie, on 23-Aug-2007 11:17

Perhaps this should be posted to Juha and make a mainstream blog via Fairfax reach to bring into the press world? Might stir a bit of thinking at the Dept of Corrections at least... This does make you wonder, is there any IT-savvy/smart person working at Dept of Corrections at all?

Comment by Filterer, on 23-Aug-2007 12:10

"It will stop some people but anybody who has a brain (ie many prisoners) will realise an exploit to get around the system is dead easy."

No the smart ones don't get caught! They are the ones that set it up for the others!

Comment by TinyTim, on 23-Aug-2007 14:05

But Steve, just because it's not impossible to get around doesn't mean it shouldn't be done. Mobile phones are very easy to get hold of and use and that's why the problem is rife. Whereas any alternative is going to be that much more difficult to set up, is going to need outside support (e.g. WiFi access point) and isn't going to be as reliable (2.4GHz through prison walls isn't going to work nearly as well as 800MHz). Yes alternatives may develop but they certainly won't be accessable to every single prisoner like mobile phones are. I'd hazard a guess and say that a bigger problem would be the risk of prisoners finding a corner of the prison where mobile phones do actually work.

Comment by barf, on 23-Aug-2007 18:06

they have metal workshops in some prisons

it would only take one prisoner to build a mini-Yagi-Uda and the rest would catch on.

Comment by dan, on 28-Aug-2007 08:21

Steve, They may not be providing a complete solution, but I certainly don't think they've "got it all wrong". Now we all know that one can't produce an entirely secure/foolproof system: there are always loopholes, workarounds, and the odd exceptionally clever person (eg: Teen cracks Aussie government's $93m porn filter). How far should they go to prevent unauthorized inmate communications? At what point do they start cutting off fingers to stop inmates using keypads? I think jamming cellphone communication is a reasonable step.

sbiddle's profile

Steve Biddle
New Zealand

I'm an engineer who loves building solutions to solve problems.

I also love sharing my views and analysis of the tech world on this blog, along with the odd story about aviation and the travel industry.

My interests and skillset include:

*VoIP (Voice over IP). I work with various brands of hardware and PBX's on a daily basis
  -Asterisk (incl PiaF, FreePBX, Elastix)

  -xDSL deployments

*Structured cabling
  -Home/office cabling
  -Phone & Data

*Computer networking
  -Mikrotik hardware
  -WAN/LAN solutions

*Wireless solutions
  -Motel/Hotel hotspot deployments
  -Outdoor wireless deployments, both small and large scale
  -Temporary wireless deployments
*CCTV solutions
  -Analogue and IP

I'm an #avgeek who loves to travel the world (preferably in seat 1A) and stay in nice hotels.

+My views do no represent my employer. I'm sure they'll be happy to give their own if you ask them.

You can contact me here or by email at stevenbiddle@gmail.com