As I’ve blogged over at Tales of the Sausage Factory, my even snarkier and wonkier blog, a company called CellAntenna continues to try to leverage the problem of cell phone smuggling into prisons t expand its product line. Sadly, they keep gaining momentum, as lots of people (particularly prison wardens) would like to believe that a new tech gadget can solve their problems. Not only have a bunch of prison wardens filed a Petition for Rulemaking at the FCC, but they are backing a bill that would require the FCC to authorize cell phone jamming in prison.
You can find general background on CellAntenna, their quest to monetize security breaches in prisons, and why this is a bad idea in my Wetmachine post. Also, in preparation for tomorrow’s Senate Hearing on the issue, we have sent this letter (press release here) to Chairman Rockefeller and Ranking Member Hutchison. We’ve also put up another Five Minutes With Harold Feld giving the short version of why this is a really bad idea. But to run through a few headlines:
1) It won’t work. As this Wired article notes, you can beat the jamming with a few pieces of aluminum foil. That doesn’t even consider the human element that prison personnel compromised enough to smuggle in cell phones can also diddle the jamming system.
2) On the other hand, as noted by frequency coordination managers, public safety orgs, and commercial licensees like CTIA, this is very likely to screw up legal wireless communication. I will note that while CellAntenna is real big on applying for permission to do flashy demos under controlled circumstances, they don’t seem terribly eager to submit any actual engineering data to back up their claims that they can jam contraband cell phones in prison areas without interfering with (a) authorized phones used by guards, (b) neighboring public safety frequencies, or (c) anyone outside the prison.
3) OTOH, while this probably won’t do squat to solve the problem of contraband cell phone use, it almost certainly will make it a heck of a lot easier to get cell phone jammers in the U.S. Which has the potential to create real problems for commercial and public safety communications generally.
4) If we really want to address the problem, we need to do better than fake security from expensive new gadgets that won’t work. Cell phone network operators can work with prisons to block all but explicitly authorized phones (called “white listing”) or can monitor cell traffic that originates in prisons that comes from unauthorized sources. We can also reduce the outrageous cost of collect calls from prisoners to their families. As Beiser’s Wired article notes, most prisoners use contraband cell phones to stay in touch with their families because they cannot afford the high rates of prison calls. This makes renting cell phones to prisoners extremely lucrative. Reduce the profit from renting contraband cell phones and you reduce (although do not eliminate) the incentive to bring in cell phones.
Hopefully, folks will wise up to CellAntenna’s scam. It’s not just that bad, easily circumventable security is worse than no security. It’s not just that money spent on jammers that leak like sieves could go to measures that would improve security in prisons and crackdown on contraband. It’s that authorizing this stuff is actually dangerous for everyone who uses wireless — which these days means everybody.











“1) It won’t work. As
“1) It won’t work. As this Wired article notes, you can beat the jamming with a few pieces of aluminum foil.”
This presumes one can physically get to the antenna(s) or radiating coax in order to encase it in the tin foil AND connect the foil to the shield or earth.
“That doesn’t even consider the human element that prison personnel compromised enough to smuggle in cell phones can also diddle the jamming system.”
Now this is a valid argument.
“2) On the other hand, as noted by frequency coordination managers, public safety orgs, and commercial licensees like CTIA, this is very likely to screw up legal wireless communication.”
It’s my observation that these entities actually have little engineering talent on hand, especially that required to design and implement complex wireless systems. The very technologies and methodologies that accomplish the interleaved and FDD services of current CMRS and PS systems can be employed to band, channel and propagation limit a jammer deployment. Further, CellAntenna not withstanding, if the FCC were to permit such jamming, it’s most likely the major manufacturers of cellular/PCS/ESMR equipment would enter the market with very high end equipment specifically to avoid adjacent channel/service interference … Just as they do now with their BDA offerings.
As always, one needs to look at the engineering properly and thoroughly, despite the fact it may not support one’s policy goals.
Henry Cohen
Production Radio Rentals
Alternative view on cellular jamming in prisons
Although Harold and I usually agree on most issues, I respectfully disagree with him on the cell phone jamming issue.
See my blog,
http://spectrumtalk.blogspot.com/2009/07/harold-feld-and-i-usually-agree-on.html
for an alternative viewpoint.
Michael Marcus (FCC Retired) Marcus Spectrum Solutions, LLC Cabin John, MD www.marcus-spectrum.com spectrumtalk.blogspot.com/ (blog)