# Jamming cell phone signals in public venues **URL:** \ **Category:** Factual Questions\ **Created:** [December 30, 2005, 3:53am UTC](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679 "2005-12-30T03:53:41Z")\ **Posts on this page:** 13\ **Page:** 2
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [January 1, 2006, 8:32pm UTC](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679/21 "2006-01-01T20:32:10Z")
> [@RandomLetters](#): > > Now, are they any laws that say you can’t passively block cell phones within an area - i.e. when you build the building, have a metal mesh of the right spacing to block the radio waves used by cell phones included into the walls? That’s apparently quite legal. Once, shortly after the subject first turned up, I heard it being kicked about on a local talk radio station. One of the more interesting callers was a guy who claimed to have a construction business that did that - he RF shielded existing buildings. He admitted that the rub for most business owners was that it was very expensive. Most of his customers were medical clinics who are quite anal about RF interference (good. let’s err on the side of caution.) But if some restaurant owner wanted to pony up thousands of dollars to have him shield a small space, he’d do it for them. ---
**Author:** ![jasg](https://avatars.discourse-cdn.com/v4/letter/j/f0a364/32.png) [@jasg](https://boards.straightdope.com/u/jasg)\ **Post date:** [January 1, 2006, 8:33pm UTC](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679/22 "2006-01-01T20:33:29Z")
What about ‘old fashioned’ beepers for health care workers? Also, as stated - this concept is not new… [TOG](http://www.asktog.com/columns/036Cellphones.html) proposed it over five years ago. ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [January 1, 2006, 8:37pm UTC](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679/23 "2006-01-01T20:37:39Z")
The metal mesh idea is called a farady cage. Maybe the proper name ought to be capitalized; I dunno. It seems like Home Depots in general are very good farady cages. The idea is passive blocking; the mesh is spaced at some multiple of the wavelength of the cellphone band, which makes it act like a very greedy antenna, so you don’t get your call. Yeah, even if you’re a doctor. Just because you may have to save someone’s life doesn’t give you the constitutional right to tell a private landowner/business that they must provide for your ability to receive on-call messages. That’s your own problem. Find a business that doesn’t block your messages, you know: vote with your dollars. ---
**Author:** ![6\_6\_6](https://avatars.discourse-cdn.com/v4/letter/6/e0b2c6/32.png) [@6\_6\_6](https://boards.straightdope.com/u/6_6_6)\ **Post date:** [January 1, 2006, 11:26pm UTC](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679/24 "2006-01-01T23:26:35Z")
> [@Balthisar](#): > > The metal mesh idea is called a farady cage. That would be a **Faraday** cage. Michael Faraday, the discoverer of electro-magnetic induction, electro-magnetic rotations, the magneto-optical effect, diamagnetism, field theory and much else besides… [Royal Institution of Great Britain](http://www.rigb.org/rimain/heritage/faradaypage.jsp) ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [January 2, 2006, 9:00pm UTC](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679/25 "2006-01-02T21:00:35Z")
> [@jasg](#): > > What about ‘old fashioned’ beepers for health care workers? > > Also, as stated - this concept is not new… [TOG](http://www.asktog.com/columns/036Cellphones.html) proposed it over five years ago. This doesn’t solve the problem (cell phones can vibrate just as well as beepers can), and it introduces a new one: Beepers can’t give as much information immediately as a person talking on the cell phone. ---
**Author:** ![Mr.Slant](https://avatars.discourse-cdn.com/v4/letter/m/c57346/32.png) [@Mr.Slant](https://boards.straightdope.com/u/Mr.Slant)\ **Post date:** [January 3, 2006, 1:10am UTC](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679/26 "2006-01-03T01:10:55Z")
> [@yabob](#): > > SNIP One of the more interesting callers was a guy who claimed to have a construction business that did that - he RF shielded existing buildings. SNIP Interestingly enough, one of my friends has a business doing the opposite. He installs amplifiers inside of buildings that have become inadvertant Faraday cages. Teh suck part of the business appears to be that you’ll need an amp for each of the technologies you’re boosting. That means you’ll wind up spending $900 x Y x Z, where Y is the number of technologies you’ll be accomodating and Z is the number of amplififers needed per building. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 3, 2006, 2:04am UTC](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679/27 "2006-01-03T02:04:27Z")
The GPS aspect of the OP is flawed I think, in several ways: -GPS doesn’t work very well indoors -In any case, the location methodologies built into mobile phones is based on triagulation and/or differential signal delay from local transmitters and the accuracy is variable, but at best is less accurate than proper Satellite GPS - perhaps only accurate to multiple tens of metres under ideal conditions. -Perhaps a minor point, but sending instructions to phones to turn them on or off, unless it could be implemented as a modification of some existing function, will require network bandwidth - individually minuscule, but might globally add up to quite a bit (admittedly, the costs of this would be convered by the subscription the OP mentions). ---
**Author:** ![Excalibre](https://avatars.discourse-cdn.com/v4/letter/e/898d66/32.png) [@Excalibre](https://boards.straightdope.com/u/Excalibre)\ **Post date:** [January 3, 2006, 4:41pm UTC](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679/28 "2006-01-03T16:41:29Z")
> [@Derleth](#): > > No. This solution is not robust enough and, quite frankly, wouldn’t work very well even in ideal conditions. In less than ideal conditions, it could kill someone. > > (The sign announcing cell-blocking signals wasn’t posted precisely right, the doctor got a call while he was waiting for someone to talk with about the blocking, the 16-year-old twerp assigned to run calls out gets waylaid by an attractive female, etc. etc. etc. _ad nauseum_ Not a good solution.) I hear what you’re saying, but I have to think that doctors managed being on call before cell phones were ubiquitous. I don’t understand why a device that most of us didn’t need five years ago has suddenly become _essential_ to the operation of society. I think, though, that if the cell phone companies could be talked into adding such a feature, automatic vibrate mode when in movie theaters and restaurants would solve a lot of these problems. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [January 3, 2006, 6:18pm UTC](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679/29 "2006-01-03T18:18:10Z")
The ringing of the phone is a minor and short lived annoyance. It’s the BLAH BLAH BLAH that invariably follows that is the real problem, and a vibrating ringer does nothing to stop that. Yes, the owner can take the conversation outside, but if they are polite enough to do that, then they probably put the phone on vibrate anyway. ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [January 3, 2006, 6:46pm UTC](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679/30 "2006-01-03T18:46:18Z")
Doctors and other people who spend most of their lives on call are probably not the problem here, because they’ve probably been on-call since the days of pagers and know to keep the things set to silent. Plus, if they get a call, they’re going to leave the theater to take it, both for patient confidentiality and to make sure they can hear what’s going on on the other end, rather than try to be heard over the sound of the latest blockbuster (and all the people yelling at them…). My guess would be that the people who are most annoying with this are either not common users of cell phones (the ones who see the Best Buy notice at the beginning of the movie and either have no clue whatsoever that their phone is on), in which case no amount of education will help, or they’re jerks, in which case no amount of anything except blocking will help. A problem with remotely switching the phones to silent ring is that some people leave their phones in their bags or coats and put them in the seat next to them and don’t notice they’re going off if they’re on silent. The big problem with legalities here is that it’s generally tricky to make being an idiot or a jerk illegal. Just ask the mods, here. ---
**Author:** ![RogueRacer](https://avatars.discourse-cdn.com/v4/letter/r/7ab992/32.png) [@RogueRacer](https://boards.straightdope.com/u/RogueRacer)\ **Post date:** [January 4, 2006, 4:23am UTC](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679/31 "2006-01-04T04:23:14Z")
> [@Derleth](#): > > So why should a person who saves lives be unable to have one 3-4 days a week? > > Your argument, however, is beyond saving. Call it. I spent three years on call while I was in the military (bomb disposal). We had vibrating pagers. When I was on call, I couldn’t do anything that took me far from the base. It came with the territory. If a place would have had signs posted saying that cell phones or pagers wouldn’t work inside, I wouldn’t have went. It would have been my responsibility. I really don’t see what the issue is. ---
**Author:** ![MsRobyn](https://avatars.discourse-cdn.com/v4/letter/m/90ced4/32.png) [@MsRobyn](https://boards.straightdope.com/u/MsRobyn)\ **Post date:** [January 4, 2006, 11:15am UTC](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679/32 "2006-01-04T11:15:04Z")
“On-call” to medical personnel can mean something quite different. A bomb technician can’t do his job over the phone – s/he has to go in and physically defuse the bomb. A doctor/nurse/pharmacist/whoever can often solve a problem over the phone. For example, a doctor might leave orders to have the nurse call him if the patient’s blood pressure exceeds certain limits. If the nurse calls him, it’s often a simple task to order medication or lab tests or whatever over the phone. The patient is taken care of immediately, and the doctor’s night out isn’t ruined. Contrast that to the old way, where the patient had to wait for the doctor to come in and write orders. When my father was taking call, he’d get tons of calls a night. Most of them were from nurses with questions about particular medications. If he had to go out, he’d just forward the house phone to his cell so he could take these calls. If he needed to go in, he needed to go in, but he wasn’t on call so much that he couldn’t have a life. Robin ---
**Author:** ![Cerowyn](https://avatars.discourse-cdn.com/v4/letter/c/82dd89/32.png) [@Cerowyn](https://boards.straightdope.com/u/Cerowyn)\ **Post date:** [January 4, 2006, 5:51pm UTC](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679/33 "2006-01-04T17:51:33Z")
Cell phone blockers are not illegal in Canada, although there are restrictions on where and how they can be used. I do not buy the argument about on-call doctors, because it is absurd to suggest that we are yet at the stage where cell phones are reliable enough to be depended upon for life and death situations. I’ve had situations all over the world where my cell phone has failed inexplicably to ring when calls were coming in, despite apparently having adequate signal. Sitting at my desk _right now_, I have the maxium signal my Treo can represent, and yet if I call my cell number it goes straight through to voice mail. [Previous page](https://boards.straightdope.com/t/jamming-cell-phone-signals-in-public-venues/337679.md?page=1)