Cell Phone JammersThursday, July 23, 2009
Operating devices that jam cell phone signals is currently illegal in the United States, but that does not stop people from selling them. It is easy to buy devices on the Internet that will jam wireless signals for cell phones, GPS signals, Wi-Fi systems, and more. Jammers work by flooding an area with noise that covers the radio bands to be jammed. Since they are cheap devices that are not approved by the Federal Communications Commission (FCC), they often spew noise out into other bands as well. One U.S. cellular band is adjacent to the 800-MHz band where Nextel, some public safety, government, and business radio systems are deployed, so chances are good that these signals will be jammed along with the target bands.
Many people do not know that jamming is illegal and jammers are being used inside schools, restaurants, and other places where owners want to stop people from placing and receiving phone calls while they are inside. Lately, prisons have begun to look at deploying jammers to keep their inmates from being able to use cell phones from jail. It is illegal to have a cell phone inside a prison, but again, that does not seem to stop inmates from possessing them.
Recently, a number of prisons have come together to ask the FCC to permit jamming inside their walls and are awaiting a ruling. There are a number of issues with this way of "fixing" the problem, the greatest of which is that the guards won't be able to use their cell phones, and if the prison's radio frequency is near one of the cell phone bands, there is a good chance they won't even be able to use their walkie-talkies. If ambulance, police, or fire personnel are called into a prison and their radio system is in the 800-MHz band, there is a strong possibility that once inside the prison gates they will lose their own communications.
The real solution is NOT to authorize jammers. Since most people do not understand the consequences of installing a jammer, that could start a stampede from others who believe that if prisons can use jammers they should be able to use them.
As cell phone system subscriber, I expect to have the right to use my phone almost anywhere. Where it is not welcome in places such as doctors' offices, theaters, and certain restaurants, a sign is usually posted to inform those who enter that cell phones are not to be used inside. Mel Samples, who heads up a wireless consulting firm in Los Angeles and with whom we have worked closely over the years, has a better approach to the problem of cell phone usage in prisons. In a recent posting to the Private Wireless Forum, a Yahoo Special Interest Group, Mel put it this way:
I just can't take it anymore.
I must be missing something.
- In order to provide coverage within a prison, any given cell carrier must
have a (or 2 or 3) nearby cell site.
- The tx power is known and fully controllable for both the site and the
registered subscriber equipment on a real-time basis.
- The carrier probably already knows what site, sector, and power level is
required to process a call from within the prison.
- Add to above: mandated location technology for cellular systems force the
carrier to know, with a fair degree of confidence, which phones are, more or
less, INSIDE the fence line of the prison.
- Prisons probably do not rely on cellular services for their routine
operation so cell service is primarily for the convenience of the "guests"?
(Though the prison could apply for GETS or some other non-public, priority
class of service if needed.)
It would seem like the carriers have it in their direct control to set
system parameters that go something like:
- Do not process (or automatically force-drop) any call that originates
on cell site XXX, sector Y, above power level z, and not class of service 1
- This could be further augmented with GPS fence lines already in the
So is anyone talking to CTIA or the carriers themselves?
It would seem like a carrier initiated and managed service area solution
would be more palatable than trying to roll back a rule that has every
marking of delivering unintended consequences.
As Mel has pointed out, there is at least one way technology can be used to prevent the use of cell phones from inside a prison. Of course, the real issue is how cell phones get into the prison to begin with. It seems to me that those responsible for the prison systems are admitting that they cannot do their job and are looking for ways to disable cell phones that have slipped by them, but jamming signals and shutting down portions of the radio spectrum is not the way to cure the problem.
Unfortunately, there are many instances where jammers are deployed, including inside schools, churches, and restaurants. Obviously, the devices are bought on the Internet from companies outside of the United States. They are shipped into the United States and deployed by people who don't understand the radio spectrum, don't know there are laws against their use, or have chosen to ignore the laws.
I hope the wireless industry and the leading wireless associations including the CTIA, APCO, NPSTC, and others will fight the prisons' request to be able to deploy jammers. If not, we could see a proliferation of them and the results could be the loss of life or property due to blocked wireless communications.
The spectrum that is being jammed is licensed to the network operators, and their job is to provide as much wireless coverage as possible. Jamming to keep criminals or impolite wireless users from using their phones is not a satisfactory way to fix either problem. In the first instance, it is the prison's responsibility to make sure there is no contraband in the prison, and in the second case, it should be up to those of us who are polite in the way we use our phones to help educate those who are not.
The push by the prisons was started by the South Carolina Department of Corrections and a copy of the petition to the FCC can be found at http://www.doc.sc.gov/news/SCDC_Petition_for_Rulemaking.pdf. It should be noted here that South Carolina has a statewide communications system in the 800-MHz range and it would be rendered useless in and around all of its prisons if this passes.
If you object to jammers becoming legal in the United States as much as I do, keep your eye on this petition and be prepared to file comments against it in the near future.
Andrew M. Seybold