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Ask Slashdot: How To Stay Ahead of Phone Tracking ?
An anonymous reader writes "In the last few years there has been a significant upsurge in subverting the cellular network for law enforcement purposes. Besides old school tapping, phones are have become the ideal informant: they can report a fairly accurate location and can be remotely turned into covert listening devices. This is often done without a warrant. How can I default the RF transmitter to off, be notified when the network is paging my IMSI and manually re-enable it (or not) if I opt to acknowledge the incoming call or SMS? How do I prevent GPS data from ever being gathered or sent ?"
As you know, they can track you even when the device is off, unless you've taken the battery out.
Turn your phone off when you aren't using it. Do you really have to be contactable 24/7? I suspect not for most people and if your phone is off then you cannot be tracked.
Turn off phone, remove battery.
You can always switch to HAM radio and connect your home phone up to your home transceiver and use a mobile transceiver.
Can you use a one-time-pad to send a character sequence to allow dialing or enable you to pick up the hook at your home?
You're not obscuring the message...
If you want to receive calls or SMSes, you need to leave the phone on and transmitting:
When a call for your number comes in, the incoming call is NOT transmitted nationally. Only in the GSM-cell that you are actually in is the signal transmitted. So, the system has to know in which cell you are to be able to "call" your phone. If you properly turn it off, the phone will tell the GSM network it is going off. So when a call comes in, it will go to voicemail immediately. If you yank the battery, the system will assume you are still in that cell where you last had the phone on, but it will probably time you out if it doesn't hear from your phone for a while. (which happens naturally if for example you drive out of range).
You can't.
Those are functions performed by the baseband software stack, which cannot be modified by the end user. Also you can't be simultaneously connected and not connected to the network anyway. If you don't want to be tracked by the network, don't use a cellphone.
Can't work. Your phone needs to periodically broadcast its location to the network, otherwise the network won't know which cell to route your calls to.
I suspect that's the answer you were looking for, but i'm afraid that's not an answer. Something like this would probably require hardware switches to be truly effective. It's much simpler to take out your battery as a few others have already stated. and dont forget to discharge the device by holding in the power key for a good 10-15 seconds.
The phone network isn't designed in a way that would allow you to not send your rough location every once in a while and still receive incoming messages or calls. Unless your phone regularly reports to the cell that it's in, the network will assume that the phone is off and not send anything to you. The network can page your last known location and even widen the search for your phone to a larger area when you get an incoming call or message, but if it hasn't heard from your phone, then it won't - and you can't make it, except by having your phone talk to the network in regular intervals.
That was one of the big advantage of pager networks over the mobile phone networks: Without a transmitter in the pager, there was no way of knowing the location.
I would say a good start is to just use the airplane mode of your phone. That should disable your RF transmitter. But of course you wont be notified when the network is paging your IMSI. The save option is to use a phone with OsmocomBB, a free software implementation of the GSM stack: http://bb.osmocom.org/trac/ It has limited functionality (no GPRS working at the moment) but at least you know exactly would your phone is doing. With that, you can even run CatcherCatcher, which is able to detect IMSI catchers: http://opensource.srlabs.de/projects/catcher The supported phones are a bit outdated, mostly old Motorola phones. But there is one supported smartphone: the Openmoko Freerunner. It is pretty usable these days and is fully supported by Debian. I love it, but you will need to tinker - a lot.
Don't make them WANT to track you, listen to you, and all else you think they do !! If you want to be a criminal, suffer the FEAR !! Scumbag !!
Then you can use it on whatever terms you chose. If you use the network of someone else, you'll have to accept their terms.
Pagers are receive-only. Turn off your phone and only turn it on if you want to respond to a page. Or use a public phone, or ask to borrow someone else's phone.
register a data-only sim to your oldest relative (grand-grand-grand mother?!?!?) and only use voip and messaging clients that support encryption. Whoever's watching you will only find nothing.
mov ax,4c00h
int 21h
While you can easily make your phone "untrackable" when the phone is not in use or needing to be used, the instant that it is used to receive a call, the provider will know approximately where it is. They have to to in order for their network to efficiently route the call without wasting backhaul and spectrum bandwidth across their coverage area. If you really want to go about designing it, you could design a repeater and receiver solution. Put the cell phone in one area, say your house, and then route all incoming calls to another device. You'd likely have to actually stream the audio rather than the signal wholesale. This actually wouldn't be that hard, but depending on the end-to-end delay between your actual location and the location of the device, you could get a lot of hangups before you can formally "answer" the call.
You eat your SIM card. Anti-surveillance.
http://www.youtube.com/watch?v=m_TFheZvG6k
There's no way you can be paged without being discovered. Paging is discovery. Silent paging is always possible. Even without paging, the phone needs to be registered to a cell.
So
Switch it off or throw it away.
aaaaaaa
- Buy it using a fake id. - Ask a homeless or drug addict to buy you a prepaid phone/sim and use it. - Buy it in another country.
As other people have pointed out, there is no way to avoid tracking and still be able to get phone calls. Your best option would be to get a prepaid sim that doesn't require a name or address. Or, have a friend (or random person) register the phone for you so it doesn't show up under your name.
Then, don't use the actual phone network, but use some kind of voice over ip over your data plan. To be extra paranoid, write your own gateway that waits for a random period of time before notifying you of the call, and keeps the connection open for a random period of time afterwards, so it's harder to associate the data traffic with the phone call.
I'm not convinced that even taking out the battery is going to be a guarantee that your phone cannot be turned into a listening device or a location tracker. How do you know that the removable battery is the only battery in the phone? My computer keeps the correct time even if you yank the cord by using an on-motherboard battery that most people are not aware of. There is no reason a phone couldn't have a second integrated battery that you can't remove. Sure, eventually that battery will run out, but how long will that take? Especially if the second battery is reserved for covert purposes when that bit is flipped, not for making your phone instant-on or anything like that. Your phone could also have a bug in it with its own battery. If you don't trust the manufacturer (and all suppliers) of a physical device and also everyone who has been in contact with the device since it was made (which at a minimum requires you to be certain who those people are who have been in contact with the device), then you don't have a guarantee that it only does what you think it does.
In this day and age, fighting covert surveillance against a highly motivated and advanced attacker is a losing battle for anyone without enormous resources - and possibly even then. Google couldn't keep out the Chinese all the time, what chance do you have? If you really want something kept secret, a major concern that you should have is to ensure that you do not attract the attention of parties with disproportionately more resources than you have, because if you do then you will lose. you probably also will never know that you lost unless your attacker decides to reveal itself.
Stop using phones with GPS.
"If any question why we died, Tell them because our fathers lied."
Phone tracking was a result of the troubles in Ireland and the NATO/US need for Red trouble makers in 1980's Europe. ... your phone is sucking up details about your life as you walk around with/use it. :)
Think of an early Cyber Intelligence Sharing and Protection Act (CISPA) hardwired into every generation of phone by default.
Then came GPS, web 2.0, maps and cloud
Stop using your phone other than for family to say hi and ask for help/shopping.
Meet your people/tribe/business associates without a phone and talk face to face or in some other hi tech/no tech way.
Soon a working phone with CCTV (camera pod), facial recognition, 24/7 city wide look down drones, covert LEO in-car cameras will be filling in even more details.
Dont forget the private sector is also doing its part to link all their cameras in too
No warrants are needed. Deep extended boarder search, gang area 'random' searches, drink driving tests will all have rows of plate reading cameras, passenger face capture, driver logging, train station federal task forces, anti war mil protest watching... all add up to very deep efforts if you make a list.
All the tech used in 1950's Soviet watching, Vietnam, Iraq is now so cheap, tiny and sold to even the smallest, struggling police forces as federal 'gifts' to help with 'drugs', 'terror' or just as free 'surplus' with never ending private maintenance contracts.
The next big thing will be state level voice print records- no longer the play thing of GCHQ, NSA - expect a fake cell towers in a region of interest to do more than just log calls, numbers and record flagged people - your voice will soon be all that local law enforcement needs on any network.
Swap the phone sim all you want, better stay off the voice too.
Domestic spying is now "Benign Information Gathering"
So don't use your cell phone as a cell phone. Buy a pre-paid with no ID (if you can), use the data connection to open a VPN link, use whatever voice and IM protocols you want over the VPN link.
09F91102 no, 455FE104 nope, F190A1E8 uh-uh, 7A5F8A09 that's not it, C87294CE no. Ah! 452F6E403CDF10714E41DFAA257D313F.
As stated you cannot turn off the transmitter and have the network be able to reach your phone. However you can get a smartphone with good custom rom and kernal support. Then you can build your own kernal and be sure it has a real gps switch. You may also be able to implement filtering of the network stack bit iirc, the radio section is often a binary blob. Find a phone where you can code all thos and you may have a popular product.
Silence is a state of mime.
Even with GPS disabled or if your phone doesn't have GPS, cell triangulation allows for a reasonably accurate position of the phone. In urban areas this works well, in rural areas less so but still enough to provide someone with potentially useful information. This is a function of the cell phone network and not the GPS of your phone.
... and wrap it around your phone.
voila.
Curiously enough I saw an idea to solve this problem this morning. It's a small bag lined with material opaque to radio waves (possibly lead foil or barium, I don't know). Whether this particular implementation works or is a tin-foil beanie, again I don't know. But the concept seems to me good. With modern phones like iPhones or my HTC One, the battery is non-removable, so it isn't easy for the user to verify that all radio transmission is in fact shut down - there could still be things like, for example, passive RFID. But if you had a radio-opaque bag in which you kept your phone, you could have a phone with you in case of emergencies, without the possibility of being tracked except when you were actively using it.
I'm old enough to remember when discussions on Slashdot were well informed.
http://www.schneier.com/blog/archives/2013/03/our_internet_su.html
But... if I were going to try and confound the system which can correlate almost all of your electronic records, you'd need to have a rolling list of sock-puppets who supply proxy identifying information to the cell towers. You'd need to have a bundle of SIM cards in the handset to do this, or to have electronics which fake the same data. Then, to make sure you can actually be contacted, you need to have a call redirection system sending you SIP calls (though if you're designing the hardware for this, you can encrypt the data streams carrying your voice over the existing cell transports - note that Skype may be encrypted but we don't know how well or who has a back door key). To avoid that being a single point of obfuscation failure, it probably needs to be a distributed network of TOR-like relays across hardware and cloud providers, and even then, it will probably need to be steganographically hidden in ordinary-looking traffic.
Not impossible, but still a pipe-dream since 1993.
For the REALLY paranoid geek I have a variant. There are lots of GSM modules that are intended for installation in some equipment. They need some power source, keyboard and microphone to operate. You may use something like the simplest PIC controller for keyboard and microphone control and be sure that unless you explicitly turn the microphone on it will be off.
It will still be a beacon, but you can invent some countermeasures, too. Your controller can detect the transmission and duly warn you if it finds something suspicious, for instance, long transmission without calls. If you are STILL overparanoid you may add a GPS device that will just turn the phone off while in zones where you don't want to be tracked.
Stationary GSM module with WiFi link to your real phone (or to your second secret GSM phone) is to be added according to taste.
Sorry, that's it.
Well, put the phone in a foil bag, under your tinfoil hat ?.
You can't beat this if you are stupid enough to rely on all the time connectivity.
I am in a position to offer a perfect solution. Just move to rural Australia and move your phone contract to Telstra. They are so fucking incompetent, nobody will ever succeed in tracking you.
:-/
The only downside is that you won't be able to make phone calls either.
Dump the idiot.
That's what that battery is for - the mind control circuit. It's the only way they're keeping the people in line.
What most people don't know is that *that* is why there's a battery in your computer too! It has nothing to do with the stupid clock. The clock doesn't need the battery! You've seen the ones that work with a potato - that's proof enough that a clock doesn't need a battery. No, they have the computers programmed to reset your clock and bios after a short timeout to make you THINK you need that for the clock. And all you weak-minded losers fell for it, and the mind control circuit just keeps you believing that you need that battery.
Is it just my observation, or are there way too many stupid people in the world?
...when they just turned the border pink and we talked about... OMG Ponies!
Is it just my observation, or are there way too many stupid people in the world?
Dear Editors,
There is an 'Ask Slashdot' section for a reason. Please use it!
Thanks.
Fnord666
PS Putting "Ask Slashdot" in the title doesn't do it.
'The tyrant will always find pretext for his tyranny.' - Aesop's Fables
OMG!
It's rather easy. All you have to do is leave your phone on the back seat of your car. If you want to go to the greater lengths, you might want to consider a trailer, or possibly a train.
Both ways. RF can't cross the cage either direction.
An RF opaque bag can be made as a bag-in-a-bag. The inner bag contains your phone, and the space between bags is filled with the small ferrite beads used to turn short wire lengths into RF chokes. One caution, however, is to make certain your phone is off before you place it in the bag. It might not like the standing wave ratio. Also, all ferrite is not the same. The stuff used for transformer cores in switching power supplies only works at frequencies much lower than cellphone frequencies.
Seriously, if you're that paranoid about being traced, why even carry a cellphone?
Essentially, if you're going to turn off all the functions that allow connectivity, and disable the phone enough that you're *pretty sure* that you can't be traced, why are you even carrying it? It's going to be a non-functional pile of circuitry in your pocket, basically. If you're that concerned, then any time you turn it on you might be being traced, even if the radio function is allegedly "off".
I guess if you want to be able to call out in case of emergency, just buy a one-time phone and DON'T USE IT UNTIL YOU NEED TO. Then throw it away.
-Styopa
it's electronic warfare
I'm 30 now, so I'm just old enough to remember what it was like being part of an active social life where nobody had mobile phones, it was perfectly fine and nobody had any problems. Arranging things was no less difficult, "meet you on saturday in the pub?" you'd say on tuesday, and low and behold there they would be on saturday. They're not there? well they're not there. You'll see them soon enough, you don't need to tell them what drinks your pouring down your gullet or what you've literally just eaten. I find all that deeply arrogant, who gives a flying f**k what your new shoes look like? Nobody could care less that you're going to place A with person B, except person B, so stop telling C, D and E about it.
If you don't like being tracked then just forgo the device all together.
Get a wifi only mini-tablet.
There's enough wifi hotspots around nowdays that you're never really inconvenienced.
Yeah you're still going to be tracked by hotspot, have your internet activity watched and all that jazz, but it'll make it a lot harder for those spy agencies to mark you for the snipers.
Maybe if enough people get rid of their mobiles the governments will stop spending money on tracking them and maybe spend it on saving lives and feeding starving children instead.
My solution is to stay a Sprint subscriber, that way I am never near any towers and if I see more than 2 bars I know the FBI is close.
load "$",8,1
This dispite the fact that several courts rulled that it is unconstitutional and forbiden them from doing so without a warrant.
I suggest you obtain or construct a small faraday cage to keep your phone in when you don't want to be tracked.
The only really secure way to turn of a smartphone is to remove the battery. Get one where you can do that or mod it with a switch.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
As part of the new KGB-Plus service available as an option on many plans, the wireless provider can have genetically modified carrier pigeons enhanced with bloodhound DNA find and alert you anywhere in a growing number of metro areas. The specially-trained pigeons will carry a coded message that only you will understand to tell you to turn on your phone and prepare for an incoming call or text message, or to seek a safe house/shelter should your identity and location be discovered by unknown forces.
http://blogs.cisco.com/security/announcing-cisco-wearable-ips/
I keep it in a tin foil sleeve.
How can I default the RF transmitter to off, be notified when the network is paging my IMSI and manually re-enable it (or not) if I opt to acknowledge the incoming call or SMS? How do I prevent GPS data from ever being gathered or sent ?"
Can't be done unless you are able roll your own hardware and redesign the cell system to not require a phone to do a hand off to the next cell. Another way would be to be politically connected and also be able to afford one of the "secure" phones reserved for government officials).
GPS data is required by Federal mandate for 911 tracking and cell tower tracking will always work regardless.
if you really have something that secret going on, leave phone somewhere else.. dont carry tracking device with you. :P
This is a complete quote from the relevant section of http://stallman.org/rms-lifestyle.html
Cellular Phones
I refuse to have a cell phone because they are tracking and surveillance devices. They all enable the phone system to record where the user goes, and many (perhaps all) can be remotely converted into listening devices.
In addition, most of them are computers with nonfree software installed. Even if they don't allow the user to replace the software, someone else can replace it remotely. Since the software can be changed, we cannot regard it as equivalent to a circuit. A machine that allows installation of software is a computer, and computers should run free software.
When I need to call someone, I ask someone nearby to let me make a call.
As a ham radio operator myself, reading some on GSM and other standards, a little on OpenBTS, and what the military (especially black ops like CIA) have done in these kinds of situations, I think I can reliably state this:
1. *ANY* radio transmission can be tracked to its source. If your phone on, it can be triangulated automagically by the base stations around you, although modern E-911 compliant ones also assist in this. In addition, the TIMING can be used to trace your distance from even one cell site (think latency/ping), so you can get a radius (similar to GPS, if I've read right).
2. The only way not to be tracked in this fashion is to turn off all radio transmitters on your person or nearby that can be associated with you. This includes wifi and can even include bluetooth in radio-quiet locations. Bear in mind you can fingerprint individual transmitters, to the point there are commercial transmitter fingerprint readers readily available: these are usually used when dealing with jammers, but you can track anyone with these.
3. None of this precludes them putting an active tracking device in your phone (I've read the battery can be replaced with a smaller one with a device included), your car, jacket, etc. These were being done during the cold war; the only difference is that you can buy them online now! And don't even get started on passive methods like lasers-on-the-windows, Van Eck, etc.
4. Jamming just keeps you from making calls: your radio can't hear the base. The base can still hear you just fine (under normal circumstances).
The bottom line: you'd have to do like RMS does and not carry one...though I wonder how useful that is since his entourage probably are loaded with them!
Don't carry a cell phone with you unless you think you will actually need it. Leave it at home most of the time. Lend it to a friend to establish an alibi.
And when you are in a situation where you don't want to be tracked but still want the phone around in case of emergencies take the battery out. If you are handy with a soldering iron make an external kill switch. Also try experiments with a RF blocking bag to see what the effect on battery life is with your phone. Consider having spare batteries.
It wasn't that long ago when most people didn't have these devices. Really, they aren't particularly necessary for daily life.
Also put your EZPass transponder in the foil bag instead of leaving it on your dash all the time. Especially when you are doing something that you don't want coming out during divorce proceedings.
if you have a phone. What would be really neato is if the people who make ROMs for Android phones could build in something that strips off location data or even allows ID spoofing.
For legal purposes, I think the police would have to prove that the phone was in your possession if they wanted to use tracking data against you in court, and likewise if you wanted to use it to defend yourself you'd have to prove you were in possession of the phone at the time the location data in question was generated. I don't know how easy that would be unless you were texting photos of yourself...
US Patent 7751826 - Motorola submitted the patent in 2002, it was issued in 2010:
US Patent 7,751,826
The Federal Communications Commission (FCC) has mandated that, by December 2002, all cellular telephone carriers must market handsets capable of providing an emergency locator service. This emergency locator service, known as E911, will enable personnel at the public safety answering point (PSAP) to pinpoint the location of a cellular telephone user dialing 911. This FCC mandate further requires that the user not be able to override the emergency locator service in the case of a 911 emergency call.
This technology has raised public concern that, in addition to being used for emergency location, the locator service may be used by cellular carriers or by others to track the movements of cell phone users without their consent. There is therefore a need for a system that complies with the FCC mandate for location service while providing maximum privacy protection for cell phone users.
The invention overcoming these and other problems in the art relates in one regard to a system and method for selectively activating or deactivating E911 tracking service, in an embodiment by disabling power to GPS locator circuitry in a cellular telephone until the key sequence "9-1-1-Send" is detected. In one embodiment, the power to the GPS circuitry in a cellular handset may be activated by detection of a keypad sequence and the rotation of a physical switch to permit power delivery. When the handset detects the key sequence "9-1-1" it may output a signal that loads the switch into a "ready" position. When the user presses the "Send" button, the switch closes, enabling power to be delivered to the GPS circuitry. In other embodiments, the selective delivery of power may be controlled by software.
Motorola has been building phones for more than a decade in which the GPS circuitry is physically separated from electrical power until the user does something that causes it to be connected. This obviously doesn't help you if your phone has been hacked or modified and it doesn't help you avoid network triangulation, but it makes you wonder how all these supposed experts know all about the "dangers" of cell phones without having done much research or talking to the people who actually made the phones (you know, the inventors of patents are listed on the patents).
Example use cases:
And *poof*... you are off the grid.
- First they ignore you, then they laugh at you, then ???, then profit.
Put your phone in an aluminum foil pouch. (See Faraday cage) Take it out to check messages/make calls.
All you need is an empty potato chip bag.
-- My hovercraft is full of eels.
2 years back I got a call from a 'friend' one morning on the 'feature phone' I owned then, and he asked me with a suspicious tone to his voice, "Uh, ... where are you?" I told him at my local library, and he hesitates, as if he's doing something else at the moment. Later on I learned why, that guy had a black market phone signal tracking program (that was given to him) running on his home computer. Not being a very computer literate person, I later realized that when he hesitated, he was really trying to understand why where I claimed to be wasn't where his program said I was, because there weren't enough towers available at that location to get a proper lock on the phone's location.
That one phone conversation was what began me googling for information about cell phone tracking, until then I was ignorant of this technology. Less than $50 and some googling for sites to download the program from is all that's needed to track a phone. Enter the phone number into such a program and a map will appear on the screen with the phone's location clearly displayed. It's an easy way to invade someone's privacy, and in my opinion it's done by people who are without a clearly defined sense of proper morality. That's rather a sad reflection on those who do track others just because they can, but what can a person do to prevent it from being done? It's a sad fact of living life in today's modern, tech-filled world.
[citation needed]
Since Slashdot posts are not truly anonymous I can't answer. The geeks running Slashdot will fall under the pressure from some government agency trying to locate me. So I'll just say that Slashdot is not safe for my comments on this topic.
Not very useful. You don't need for the device to provide its location with GPS, the network can deduce it with no specific device support (except complying with the cellular standard for replying to the network pages and request for cells measurements). Google "RF pattern matching": it's 100% network side, and is more accurate than GPS in urban and semi-urban locations so cutting the GPS won't help at all here (and most people live in such environments nowadays). RF pattern matching is already deployed in some 2G/3G networks, and is currently being specified for future LTE evolutions.
In rural environments using the device GPS is still the most accurate method, but even then the network can provide a reasonable location estimation based on the device reporting the receive power of its serving and surrounding cells (a standard function, which is used to drive handover). And cellular networks do support this as not all devices have GPS.
Threat model:
http://en.wikipedia.org/wiki/Enhanced_9-1-1#Requirements
Mitigation:
1. remove power from phone (battery) when not in use
2. carry phone in faraday cage when not in use
3. place GSM jammer close to phone when not in use ($50 online from CH)
4. use new pre-paid GSM phone (no ID requirement) every two weeks
5. use multiple sim cards and gsm phones in a non-repeating patern (eg use Ph1 on Monday, Ph2 on Wed., Ph3 on Thurs.)
It has its own set of issues, but one could use VOIP over wifi & VPN as well.
I have an RF detector, it's called my PC desktop speakers. I get static on the speakers any time the :-)
phone is near and "phoning home". Dual use speakers are lot cheaper than buying a real RF monitor.
I wonder how feasible it would be to come up with a small field-strength indicator that at least lets you know if your phone is transmitting significant amounts of data when you don't expect it to. It's not too hard to construct such a device with older, modulated-carrier type radios, but it might be more difficult with a CDMA or other wide-spectrum device. Also it would be prone to false detection of other nearby cellphone radios. However I think it's your best bet for taming a commercial cell fone.
Then again it is easily thwarted by an app which stores compressed audio/location data on the fone and bulk uploads it whenever other traffic is occurring.
Measuring power draw of the battery might tell you if something is running when the phone is 'off'. It won't help you if the spying app is only active under normal operation, however.
As I'm sure many others have said, you could use pre-paid phones and recycle them every so often. Then again it may be pretty easy to identify you based solely on the people you call with that phone, along with other biometric information(voice indentification, for instance).
I think we're all going to have to get used to being tracked, scanned, inspected, detected and infected. What we should be doing is establishing a legal framework that offers us clear protections and a method of redress when our rights are violated. I think we're entering this new era blind - most Americans and even government officials can't even comprehend what's coming or what is already here.
We live in an age when most people don't have a clue why the bill of rights exists as it does, so the chances of success are not good.
http://www.masturbateforpeace.com/
I wasn't tops in physics, but the lecture on Faraday cages really stuck with me - no ifs ands, or buts about how it completely separates the inside from outside electromagnetic worlds. So rather than running around pulling out batteries or modifying your phone, what's so hard about a metal phone case?
You may not need a tinfoil hat, but a tinfoil pouch may not be paranoid...
Even if you could micro-manage the transmitter of your cellphone, the network isn't going to send it a page unless it knows that your cellphone is on (responding) and what group of cell sites it's within. So, your request to know when your phone is being paged, but not otherwise have your phone transmit anything isn't going to happen. Due to E911 requirements, to minimize the cells over which your page must be sent, and also to manage handovers between cell sites, the network has a pretty good idea where your cellphone is whenever it's on. But, for the paranoid, you can work around this limitation, if you're willing to make a few sacrifices in response time: 1) Keep your phone either powered down or in airplane mode. By "powered down" I mean turned off; no power being drawn from the battery. Not just that the screen isn't displaying anything, but really turned off. Not in "sleep" mode, but actually turned off. You don't have to remove the battery, but you do have to be certain that it is turned OFF, not in some sleeping or standby state. If your phone has "airplane mode", this is just as good, but only enable WiFi when absolutely necessary. 2) Let your callers leave voice mails. Knowing when they called can now get interesting: For the truly paranoid, Get a pager. An old-fashioned, one-way pager. The network has no idea when or if these are on or where they are. The network simply sends pages to it blindly, in whatever area you've paid for. Configure your cellphone's voicemail to use automatic voicemail notification. This is all done in the phone company's switch and doesn't involve your cellphone.. AT&T includes this feature even on their prepaid service called Go Phone. Configure it to call your pager immediately after anyone leaves you a voicemail message. You can then call in to get your voice mail from someone else's phone. Alternatively, if your phone supports downloading of voice mail, such as iPhones do, turn on the WiFi connection, while still leaving your cellphone in airplane mode. This will allow your voicemail to download to your phone without using the cellular network. Listen to it. Then turn your phone back off. Or give up and turn off airplane mode and call the person back. But, you've now divulged where you are!. Another possibility is to get one of the T-Mobile blackberries that support UMA (unlicensed Mobile Access) which allows voice calls over WiFi. Be sure to change the name of your WiFi network regularly, so that when Google (et al) survey the area that they don't know where your SSID is.
Google requires you to activate Google services via phone. So they have the ID of the phone you used to activate and can work their way from that phone to YOU.
Instead of modifying your phone, turning it off, taking the battery out etc. you could build a mini Faraday cage. put the phone in there whenever it's not in use. :) When people ask about it tell them you've had issues with your phone running away.
Common Sense (+1)
That feature is for power conservation not user security. Many such phones keep the GPS off until an emergency call is made to extend battery life.
For the paranoids out there there is a very real possibility of your phone receiving an "update" that hides the fact that your GPS is transmitting your location. And as the other poster stated, even without GPS, your location can still be approximated from your phones normal interactions with the local cell towers.
I am becoming gerund, destroyer of verbs.
Multiple tower triangulation, which seems so obvious, is quite difficult to implement, and is rarely done. Here's why:
- if you're fairly close to a tower, then other towers are unlikely to hear you. (This is by design: cell phone towers are designed to minimize overlap in coverage, so as to maximize frequency re-use over a geographic region)
- Those times when you are in range of multiple antennas (LTE people call these e-nodeBs), it's your cellphone that keeps track of the strengths of the neighboring e-nodeBs. This list of signal strengths and interference levels is not sent out from your cellphone unless a handover between enb's is about to happen.
- communications between a cellphone and a tower is not by a single carrier, but rather using a large number of discrete frequencies (for LTE, it's orthogonal frequency division multiplex). This type of modulation is designed to resist fading and interference, but is extremely difficult to triangulate, because the databits are spread over many symbols)
Most common localization of a cellphone uses a single tower. Simply knowing the antenna that you're connected through localizes you to a sector (of about 60 to 120 degrees in angle by about 1Km to 10Km in radius). The cellphone operator's Mobility Management Entity keeps track of this in real time, so as to route your calls, forward messages, and page your cellphone. Of course, this is several square kilometers, but it's possible to do much better:
Better single-tower geolocation takes advantage of every cellphone's being kept in tight time-synchronization with the clock in the tower's enb, using "Timing Advance". The Timing Advance method, in theory, can determine the distance of your cellphone to the tower within about 150 meters, but typically an operator gets 300 to 400 meters rms. This is a radial distance from the tower to your cellphone. The azimuthal location is coarsely determined by the sectorization of the tower: most cellphone towers have 3 to 6 enodeb antennas, and so can localize within 120 to 60 degrees in azimuth. And so, in general, you can be geolocated within an annulus: it's about 300 meters in radial distance from the tower, and about 60 to 120 degrees in azimuth. A fairly big territory: probably a football field or three. These systems are very useful for locating network problems, but cannot determine your location to better than a couple hundred meters.
A few systems can improve on this. For example, Newfield Wireless has developed a high resolution method of single-tower localization, apparently using enodeB timing data combined with local geographic information. But I'd be surprised if this results in better than 50 meter resolution.
Short version: Cellphone triangulation will not track you. Single tower tracking systems can yield coarse tracking.
This setup lets you always be able to dial out, but will eventually weary your friends who don't know what number you are now. You might want to do something else for a receiving number.
You probably have a core "fingerprint" of usage that is identifiably you, but it may resemble the fingerprint of people who run in your social circle. Mix things up a little. With each new phone add a new group of numbers unrelated to the other phones. Let's say phone #1 calls a cluster of sports related numbers, # 2 local civic groups, #3 bars, taxis, and liquor stores, etc. Call them a few times with honest questions. Let the watchers burn through their budget finding out who all these new d@#mn numbers are.
If your radio is off, it won't check in with the tower. If no tower has seen you, you won't be getting any SMS messages or voice calls.
What about having a number of handsets set up in numerous static locations which are all set up for call relay. Dial the number of handset A which is sitting in your moms house, this is then relayd to another handset B at grannys house, this is then relayed onto your handset. This is effectively placing a barrier between yourself and handset A but the question is, is this traceable on either phone records or on the handsets themselves?