How cell calls and text messages are intercepted: are you concerned yours might be?

How cell calls and text messages are intercepted: are you concerned yours might be?

Summary: Those are the good intercept guys. But that doesn't represent the entire cell phone intercept universe.

TOPICS: Mobility

Those are the good intercept guys. But that doesn't represent the entire cell phone intercept universe.

The odds are vanishingly small that anyone is actually out there intercepting your text messages. But that doesn't mean it cannot be done.

In fact, an article posted last week to the online magazine Slate describes how both the good people and bad people do it.

Bad people as in criminals, and good people as in law enforcement trying to catch these criminals.

The first way is phone cloning. With this method, incoming messages can be intercepted and outgoing ones can be sent as if from your won phone. The bad guys make copies of your SIM card. They do this via SIM readers that can read your cards crypto key. Then the SIM card is transferrable to another phone.  

By the way, punishment for doing this is substantial. And, there's no firm guarantee that the phone's encryption won't be overly sophisticated.

These criminals also can do the dirty deed by uploading very, very illegal firmware onto your phone. As Slate's Christopher Beam (apt name, considering the subject, huh)? explains:

This (use of firmware) essentially turns your phone into a radio and allows it to pick up all the texts broadcast on a given channel—instead of limiting you to the ones addressed to you. You'd also need to know the network for the target phone—Verizon, Cingular, T-Mobile, etc.—and you'd have to make sure that both your phone and the target are within range of the same base station. This method isn't too expensive since you don't need much more than a computer, a phone, and some firmware that any serious techie could find online for free.

Yes, Chris, but how do they do it on shows such as CSI:Miami?

Well, if the plotline were real,they would use something like Cellular Monitoring GSM Intercept model GSM 2060TP for (hey, guess what) GSM networks, and Cellular Intercept (CDMA).

When we visit the website of Securities Intelligence Technologies Group, we don't learn all that much about either of these solutions. That's understandable, because we don't want the drug dealers and terrorists to know how we track them. Info is available, but only for registered users (ideally law enforcement types).

Here's what the company site tells us about the CDMA intercept solution:

"This cellular intercept system operates by automatically detecting the strongest signal in a CDMA service area. Working as a mobile phone intercept on global CDMA networks, the CDMA Cellular Monitor also intercepts control channels and both sides of a conversation through traffic channels."

Less specific info is offered about GSM intercept, but with relation to general intercept capabilities, we learn that: 

"All of the decryption technology is built into HSS Cellular Intercept Systems, therefore, no connection into any cellular phone network is required (as it is when using hardwire junctures or non “off the air” monitoring systems).  In addition, the audio digital recording capabilities in HSS Cellular Intercept Systems are also user friendly."

In other words, powerful decryption for text, and audio recording for intercepted voice.

User-friendly, but not budget-friendly. At least insofar as law enforcement use is concerned,  Slate mentioned that some of these solutions can cost in the $1 million range.

But SIM readers? Go Google it or eBay it. Much cheaper. Less than a tank of gas in most places.


Although there are some legitimate uses for these tools (such as enabling transfer of data from one cellphone's SIM card to another) the folks who use these tools to intercept cell calls and texts have something more wicked mind.

Are you concerned?

[poll id=55]


Topic: Mobility

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  • Well sure it is possible BUT...

    the porpetrators need access to your SIM card for starters.
    and unless you are going around giving just about everybody access to your phone that ain't happening. so for regular person it is not a big threat. Second thing with this approach is that nowdays most cell comapnies monitor connections from all phones and if two same signatures are detected it might (might not neseserly will) trigger an account suspension lock where you will need to call your provider to reactivate or recover your account status. phone clonning might have been a big issue some time ago but I do not belive it is now.(I could be wrong..)
    check this link :
    and this one :
  • Bush...

    For all of you pinheads that voted... "it's the Bush administration that I'm afraid of."

    1. Why be afraid unless you have something to hide?
    2. Are you a terrorist? See #1
    3. are you a criminal? See #1
    4. or... You're just a politically blind moron who will go against anything that Bush or the conservative side of the house has anything to do with.
  • Echelon

    Landline and broadcast communication is being actively monitored by the NSA and GCHQ as part of Echelon or its successor programs. Nothing has changed and this is part and parcel of living in a Cold War and post Cold War world.

    I don't think much about it since there is nothing that I can realistically do about it.

    Todd Smith
  • How can they copy what they don't have?

    Don't you actually need the physical SIM card in order to copy it? Or is it encoded into the signal?
    Maybe this is a problem for people in important corporate or sensitive positions of national security to be paranoid about, but I don't believe the general public should be concerned.
    There are litterally billions of telecommunications signals both wireless and cabled that would need to be monitored. The only logical approach is to have speciffic targets to monitor. Computers can monitor signals for specific keywords and phrases and then a list of targets could be assembled, but I would think they would have to be fairly narrow in scope to keep it manageable. Especially since the value of the information is usually time sensitive.
  • realistically.....

    Yeah, it's real, it can happen, but there's no reason to neither freak, or ignore.
    Loads of random info on a random person for the most part is useless.
    Yes, anyone who is a worthwhile target already has security in place.
    Yes, they physically need to copy your would either have to be someone who has been inside your house and had enough time to turn off your phone that you had lying on the desk and copy the SIM to another portable drive or send it to themselves and replace it, all while you were busy, or the disgruntled cell employee who programs the SIM before sending it to you copies mass batches.
    If you're actually concerned, you don't have to have any identity sensitive info in any texts or calls. You can make the occasional, rare call regarding a credit card and such on a land line or company phone.
    It's cute how they ordered the options in descending order of popularity, and took a stab at Bush too.
  • Um... no

    I don't think the author here fully understood the original article. Read the source on to get a better understanding for yourself.

    For example, at one point he talks about the bad guys putting illegal firmware on your phone. No. It's the bad guys that put firmware on their phone in order to use it as an interceptor. This is just one example of the conceptual errors he makes.

    He also doesn't fully understand how encryption works because after mentioning the sim card copy method, he goes on to say that "[although] there's no firm guarantee that the phone's encryption won't be overly sophisticated." Again, no. Once you have physical access to a victim's sim card, all encryption has been defeated. Sophisticated (good) encryption only comes into play when the bad guy is intercepting calls without having the victim's sim.
  • cloning - sending text through another device

    Does anyone know how someone could have their phone cloned - where text messages appear to have been sent by a device/international text charges appear to person A's account, even though person A did NOT actually make the outgoing text but someone (person B) did it remotely from another means? Person A's carrier claims it was sent from their device - what technology was used for this? Thanks, in advance!
  • It's More Than Possible...and You Don't HAVE To Be Somebody Important...

    This happened to my boyfriend's phone 2-3 months ago in order for someone to send me texts apparently from his phone but not from him that I could then reply to and they went to the hacker and not my boyfriend. No one other than him and myself had direct access to his phone to copy the SIM so how exactly would they do that? I say you don't have to be somebody important because I'm not. I've not the slightest clue why I would be targeted but I do know that it pertains (ed) to me being a researcher and a questioner. I'm just looking for some more insight on this however because before this happened and I started looking for info, I did not know this was possible. I also have screen caps of all the messages in which each message starts with a different number and other seemingly non-sensical icons.