Cordless Phones: All your base (stations) belong to us

Everyone knows that eavesdropping isn’t polite. We’ve also all had the experience of accidentally overhearing something in a conversation (in many cases out of context). Since we can hardly hold people accountable for hearing what others say within earshot, we are usually on our own to protect our privacy in such situations. This becomes a bit more complicated when you put a phone into the mix. The transmission of a phone conversation across the telephone lines is a protected form of confidential speech and recording such conversations is illegal without consent (in some states you need one party (or a judge’s order) in others, like California, you need both parties consent (or a judge’s order)). These wiretapping provisions also applied to wireless phone transmissions. What is interesting is although the government may need a warrant to listen in to your wired phone call conversations (called land lines) they (eavesdroppers) do not to listen in to your wireless calls (http://caselaw.lp.findlaw.com/casecode/uscodes/18/parts/i/chapters/119/sections/section_2510_notes.html). This is because the law says so but from a practical matter it is because wireless calls are broadcast and thus anyone who can receive that broadcast can listen in to what you are saying. Since you are broadcasting, you have no reasonable expectation of privacy (well talk more about this in another posting).

In the 80s and 90s this meant not only government listening to people’s phone calls became much easier, but that private parties could listen in with greater ease (note, there is a distinction between what people.govt. can do, and what they can do legally. Recording something might put you (or the govt. afowl of some laws, but it doesn’t stop information gathering, legal or otherwise). In many cases people would take a cordless phone handset and walk around their neighborhoods (a radio scanner would work as well) and just switch channels until they tuned into someone’s conversation. The handset method also allowed people to pickup unused base stations (where your phone rests to recharge) and use their line to make long distance calls for free (or local calls that were much harder to trace to the person making the call). Several advancements over the years have made this more difficult. Phones have moved to new frequencies (higher frequencies mean people need newer equipment to listen in but the greater range for your phone, the farther away an eavesdropper can be). Phones also started blocking the base station if the phone was in the charger (a modest improvement). Another improvement was frequency hopping (exactly what it sounds like). Perhaps the biggest change was the move to spread spectrum technology.

Spread spectrum technology spreads the conversation out over the entire frequency band. This prevents traditional monitoring tactics as any one frequency doesn’t show enough signal to make it appear that there is anything being transmitted. This technology was used by the military in WWII and only in the 90s became civilian use technology.

What is of note of all of these changes is that all of them are still able to be intercepted (though private parties have to go through more, and more expensive, loops to continue to eavesdrop government surveillance still has the ability to listen in without the burdens of a warrant that land lines require. What is also worthy of note, is that although the technology has evolved, the one thing that would seem to be the most effective way to protect the privacy of phone users (encryption) has never been offered (Another article will discuss encryption of communications).

From the user’s perspective, the critical thing here is that you are most protected from privacy invasion in your phone calls by using traditional land line communications. When you add the convenience of wireless, you are giving up some of the potential privacy of your conversation.