Privacy - cell vs. landline [telecom]

In the case of Joe Evesdropper, there was a time in the eighties and nineties when cellphones were very easy to eavesdrop on and were effectively open. The industry responded to this by railroading through the Electronic Communications Privacy Act which made it illegal to listen to them.

At some point it became clear that making laws wasn't actually going to prevent people from doing anything, and various other factors forced cellphone providers to encrypted digital signals which pretty effectively prevent evesdropping. (Although we still have the disaster of the ECPA in force).

So... there was a time when cellphones were easy to listen to with fairly inexpensive equipment, but this is no longer the case.

Now... that said... if you are talking about the Authorities rather than just some random evesdropper, then both cellphones and landlines are very readily tapped. Just takes a friendly judge to sign a piece of paper and they can listen to anything they want. And to get call records showing who called whom when no longer seems to even require that.

--scott

The data available from cell handsets is far more than simply calls.

Cell handsets are essentially personal tracking stations which can be used to record your movements and the data can be used for all sorts of nefarious purposes from general government and commercial snooping to criminal use such as analysing patterns for potential crimes such as house break-ins and kidnappings etc.

That is the sort of data collection people should be concerned about.

First of all cell phones use radio, so conversations can be recorded. While modern systems do use encryption techniques, merely recording the radio signal allows for extensive code cracking efforts (that may take a long time to actually crack things, but given enough time it can be done). There is nothing that can be done to make any radio signal absolutely secure, you can only make it computationally and time intensive to do. Usually that discourages all but the most persistant eavesdroppers. If you have a handoff to another cell that can complicate matters and require mutliple receivers. Cell sites are connected to the switch using normal telco transmission systems, so tapping into those is another way to get the info.

All switches in the modern era have a "service evaluation" port which is where the authorities can attach the recorder for the wire tap. Several years ago there was a requirement added that said the service evaluation point for a given phone had to be at one georgraphical location, a move that enabled/simplified wiretapping cell phones (Think of a NYC cell phone being used in California to call Arizona. The call normally isn't routed through NYC, but if a wiretap is authorized, it is made available in NYC).

So the short answer is that no form of telephony will allow you absolute privacy in any communication, if the government (or a persistant eavesdropper) wants to get a hold of it. Of course that requires a warrant for government authorities, but we do have some secret courts that issue those and the user likely will not know about it.

Internet communication also can be intercepted or obtained from the service providers' servers. Bottom line is that if your really want to keep a secret, meet in person down by the railroad tracks in a rural area in the dead of night under a new moon...

Eric Tappert

And (if you can't bribe a telco employee or get the info via the legal process) you can buy the gear through someplace like the Chinese marketing site Alibaba. I see several IMSI catchers for sale (price from $2K to $20K, metadata only, control the gear with a cellphone app), and one "cell phone monitor" (no price given, you might have to convince the seller that you're legit).

Getting movement data over a wide area would probably require access to the telco data, if you weren't ready to build your own (expensive) network of data collectors.

GSM voice encryption (if the cell site actually is using it, apparently not all sites do) has been cracked for years (allegedly it was designed to be weak enough so 25 years ago intelligence agencies could break it). A brief google search will turn up how to do it with free software (GNURadio/Airprobe/Kraken) and links to Software Defined Radio (SDR) hardware manufacturers ($200-$4000, depending on features) for the hardware, so just eavesdropping on a cellphone is possible for someone who wants to badly enough (assuming you can physically locate to the same celltower area).

For a land line, The Authorities need to go to the trouble of getting a court order to tap the line.

For a cell phone, all they need to do is set up a Stingray unit and lie about it, as has been routinely done by The Authorities.

On the face of it, the land line is safer. However, the smart covert op will have each party buy a burner pay-for-airtime phone. As long as they don't discuss anything that will identify them (e.g.: "Let's meet at 9 PM at the Longhorn Bar"), they're probably secure. They *must* each do this from some random location, so that the GPS and tower data doesn't locate their homes or offices. This alternative also makes the metadata useless. Some unknown phone called some other unknown phone.

Now, all of the above assumes a straightforward, unmodified phone. Add scramble capability and the game changes. See, for instance,