Your recent article on TIA left me wondering if you thought the clicks on your phone were the result of wiretapping which could generate information used to harrass you or if you knew that the clicks were the intelligence agencies playing headgames with you. Because bad detective stories say that clicks are the result of wiretapping, and most people seem to believe this, I decided to let you know the facts (which you probably already know anyway).
A click is the result of somebody in your household picking up an extension while you are making a call. A click will also occur if that person puts down the extension before you have finished the call. Both occur because phones (even dect phones and answering machines) derive the power needed to send and receive speech from the phone line itself.
If the other extension is kept open then your conversation will sound "echoey" or "boomy" or "hollow." This is because phones are rather primitive technology. They contain circuitry (a transformer) which prevents your own speech into the transmitter deafening you at the receiver. It works, as long as your phone is the only one in the household on line. As soon as somebody picks up an extension, the noise-cancelling circuitry (the transformers) interact to give the hollow sound.
If somebody is listening at another extension and you finish your call before they replace the handset, when they do replace the handset the bell on your phone, and on any other extensions, will tinkle. In some countries (such as the UK), phones and extension wiring incorporate "anti-tinkle" circuitry to prevent this happening; US phones have no such circuitry.
You will also get clicks if a lineman is checking your line. What they use for simple testing is essentially a ruggedized phone with alligator clips instead of a jack so they can clip it to the line. It has the same effect when attached and detached as somebody in your household picking up an extension.
Even back in the days where wiretaps were conducted using a tape recorder in the exchange or clipped to the line between the exchange and your house you would not hear any clicking. They were powered from the mains or a battery and used an amplifier. The amplifier has a far higher input impedance than a phone so draws no appreciable current from the line and
therefore does not cause any clicks. Even with a very low input impedance, the amplifier would only cause a click when it was initially attached and later when it was eventually removed.
These days, with digital exchanges, and FBI-mandated monitoring facilities, there is absolutely no chance of a click. It's a digital copy taken from the exchange and shunted to wherever. There is no audible indication whatsoever that this is happening.
Another possibility is that you're the victim of somebody trying to get free calls using your line. In the UK this is known as "green boxing" since the favourite place to cross-wire lines is in the green- painted British Telecom street cabinets. But if you're in an apartment building, then the box in the basement would be another possibility. Check your phone bill!
If you're hearing cyclic clicks then there are two possibilities. One is a genuine exchange fault which means that the clocks on the ISDN link between that exchange and the next one are out of synch. This can manifest itself as a regular click, and the interval between clicks allows you to estimate the difference in clock timing. The second possibility is that the intelligence agencies are playing headgames with you. They want you to believe that your phone is being tapped so that you curtail your activities and get paranoid.
So your cyclic clicks are either somebody stealing the use of your phone line, a genuine exchange fault, or the intelligence agencies playing headgames with you. Given the guy in your basement, the first and last are the most likely of those options. Take your pick.
I wouldn't be surprised if those nimrods were trying to gaslight me. I guess they haven't read much about me if that's the case. They certainly aren't having the time of their life listening to my boring phone calls, believe me.
Phone bill checks out normally.