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A Vaccine Against Telemarketers?


Fleas are parasites. They are classified as such because of the nature of the way in which they make their living. They don’t build like ants or produce something useful like bees. They don’t forage like caterpillars or hunt like spiders. No, those activities are too much work for a parasite.

The most effort a flea exerts, by comparison, is to attach itself to a host. The host does all the hard work of survival. By living among the hairs of a dog and feeding upon its blood, the flea takes from its host warmth, protection, transportation, and nutrition. What does the host get in return? Nothing--unless you consider severe discomfort and disease a fair exchange.

Figure 1: A blood-sucking flea (Source: Wikipedia.org)


There are numerous parasites in the animal kingdom. Tapeworms come to mind, as do leeches. A creepy marine isopod, Cymothoa exigua, enters a fish’s mouth through the gills and attaches itself to the fish’s tongue. It sucks blood until the tongue has withered away. It then attaches itself to the tongue’s stump and takes the place of the tongue itself. From that point on, it gets first dibs at anything that enters the fish’s mouth. Now if that isn’t the stuff of which nightmares are made, I’m not sure what is.

No matter what the particular creature, in the end, the parasite game is always played the same way. The parasite finds a host, attaches, and feeds--whether the host likes it or not.

Parasites exist among humans, too. They come in a wide variety of shapes and forms, but the particular sub-species described in this article is one I’ve taken the liberty to name myself. I call it Telephonium Parasitus, more commonly known as the telemarketer.

Figure 2: How I envision Telephonium Parasitus


If you're a regular visitor to my web site, you know where my interests lie. I enjoy sharing information on projects related to radio, electronics, and science, and to promote my books. I am not predisposed to rant or blog about politics or social issues. However, a recent infestation of Telephonium Parasitus caused me a great deal of grief, which inspired me to experiment with a potential vaccine. Bear with me for a few more paragraphs, and I’ll be happy to share with you a formula that has demonstrated some tangible benefit.

A Case Study of Telephonium Parasitus Infection

Several months ago I received a call on my cell phone from a number I did not recognize. I dropped whatever I was doing at the moment, removed my cell from its holster, and listened. What I got was a recording explaining that I should “press one” if I wanted to consolidate my credit card debt. The recording didn’t identify the responsible company. I had no debt to consolidate, and I would never give sensitive financial information to a cold-caller anyway. I simply hung up and assumed the matter closed.

A few days later, I received another call from the same outfit. I hung up. The day after that, they called again. The first few times they called, it didn’t bother me too much, though the repetition soon became tiresome. I didn’t know it yet, but my phone had become the unwilling host of Telephonium Parasitus. 

T. Parasitus began to invade my workplace, interrupting business meetings. It invaded my home, interrupting dinner, a walk with the dog, time with a book, or watching a movie with my wife.  The situation quickly passed the threshold of annoyance to the point of outright harassment.

Eventually, I got angry and “pressed one” to speak to an operator. According to information on the Federal Trade Commission’s web site, a telemarketer is required by law to identify the company or interest they work for. I politely asked the operator what company she represented and why she insisted on calling. She hung up on me.

The calls continued. Several times, I pressed one to inform the caller that I was on the National Do-Not-Call list. In each case, the telemarketer hung up before I could even finish the sentence. I’m guessing that, in some slimy technical-legalistic way, this would give them grounds to claim that they’ve never heard a request to stop calling.

Eventually, I was receiving as many as six or seven calls from these people a day. I filed numerous complaints on the National Do Not Call Registry web site, yet I saw no evidence of benefit to me or my situation. I did a phone number search on Google and discovered that whoever was making these calls, they were harassing people around the country.

Figure 3: Dealing with a telemarketer... (Source: imgur.com)


I really do try to treat other people with kindness and respect, even when I feel that they have stepped on my toes. This includes telemarketers. So, it might seem harsh that I would refer to these people as parasites. In this case, however, I offer no apology. Like the blood-sucking flea, their behavior warrants the name.

Telephones are not broadcast devices like a radio station sending to multiple anonymous recipients. When a person telephones me, they are making a private point-to-point connection, thereby entering my personal space. Moreover, to do so, they make use electronic equipment and infrastructure that I have personally paid for.  

Hey telemarketers–you have no intrinsic right to personal access to me. You have no innate right to enter the privacy of my home or workplace without my invitation. You have no right to commandeer equipment and services that I pay for to solicit me against my will. When you insist on continuing after I’ve asked that you stop–numerous times–you simply confirm how unworthy you are of any patience or understanding.

When you eventually harass me to the point that I stop responding to the ring of my phone, you’ve effectively denied me access to my own hardware. By seeking to avoid you, I miss calls from loved ones or business associates who have a legitimate reason to contact me.

When you insist on doing these things, you reduce yourself to the role of a bloodsucking parasite and me to the role of unwilling host–hence the name I've created for you, Telephonium Parasitus. Oh...and spare me the part about how I need to be cool about all of this because you're just trying to earn a living. So is a tapeworm or a tick, but that doesn't dissuade a person from trying to rid himself of it.

Existing Treatments for Telephonium Parasitus

The federal government has established a National Do Not Call Registry. In theory, you can record your phone numbers to this database and immunize yourself against calls from most kinds of telemarketers. If your phone number has been registered for at least 31 days, and a  telemarketer calls you, you can file a complaint against them on the Registry web site.

While a great idea in theory, this system was ineffective in stopping the caller(s) harassing me. Despite filing numerous complaints on the Registry web site, no apparent action was ever taken. Consensus on the Internet among victims is that the government never does take any corrective action. I temper my criticism of the Do Not Call Registry only because legitimate telemarketers seem to show some respect for it, and if it did not exist at all, conditions might be far worse than they are.

A visit to my cell provider’s “Unlawful Call” web site was no more helpful. It would appear that, unless a nuisance call contains threats of violence or bodily harm, there isn’t much that they’re willing to do to help you.

Another thing I tried was to configure my phone to associate the parasite calls with a unique ring tone and a contact name of, “Do Not Answer.” I knew it wouldn’t stop the calls, but it might save me the trouble of digging into my holster when I didn’t really need to. Unfortunately, this tactic proved ineffectual because of the tendency of T. Parasitus to periodically rotate or change its calling numbers.

Figure 4: This won't work against telemarketers... Try electronic countermeasures instead (Source: imgur.com)


A Vaccine Against Telemarketers?

For at least 50 years, telephone systems have made use of audio tones or combinations of tones to denote keypad activity or to control the behavior of phone lines and switch gear. Everyone is familiar with the “Touch Tones” produced by land-line telephone keypads. Some people have even used these tones to play simple songs.

Back in the 1970's, generation/manipulation of these tones allowed hackers to make free long-distance phone calls from any pay phone. So-called  “red boxes” generated control tones to simulate the insertion of coins into a pay phone. “Blue boxes” allowed a knowledgeable person to issue commands to the network to route his own calls. I should add, parenthetically, that these activities amounted to theft and were illegal. The phone network has since been upgraded and hardened, so red and blue boxes are now just the stuff of legend.

One set of tones that everyone hears, sooner or later, sounds like “doo-dah-deet.” It’s usually followed by a recorded message saying, “...We’re sorry, the number you have reached is not in service.” The tones and message signify a phone number that has been changed or disconnected.

According to information at http://www.thisisarecording.com, “doo-dah-deet” is more correctly termed a “Special Information Tone - Intercept.” It’s comprised of three notes: 913.8 Hz for 276 milliseconds, 1370.6 Hz for 276 milliseconds, and 1776.7 Hz for 380 milliseconds. You can hear an example of the sound here.

One day, after receiving six calls in a row from T. Parasitus, I momentarily considered canceling my cell phone service or changing my phone number. This got me to think about the automated dialer that T. Parasitus was using and how that dialer might respond to a disconnected number. Was the dialer sophisticated enough to distinguish a functional phone number from a disconnected one? What would happen if the number really was bad?

Granted, reaching a disconnected number is not big deal to a robot, but if you are a parasite whose business is dialing as many people as possible in as short a time as possible, you don’t want to waste any time on disconnected lines. In fact, if your dialer can determine that a given number is bad, it would be advantageous if the dialer was smart enough to take the additional step to purge that bad number from the dialing database.

I knew that the phone company indicated bad phone numbers with “doo-dah-deet,” and the electronics necessary to listen for and decode that tone pattern would be trivial to implement in silicon. Surely, then, the parasite’s auto dialer must have this capability.

Hmm, I thought. What if I were to record these tones on my outgoing voice mail announcement? Their dialer would hear “doo-dah-deet” every time they called me. Would this fool their dialer into thinking that mine had become a bad phone number? Would this trick their auto dialer into purging me from their calling list? There was only one way to find out.

I obtained an mp3 copy of the tones from http://www.thisisarecording.com and loaded it into Audacity. I plugged a set of walkman-style headphones into my laptop and pressed one of the earpieces against the mike on my cell phone. I set up the phone to record a new outgoing message, and pressed “play” on Audacity.

I wanted to make sure that friends and family knew that they could still leave messages, so once the tones were complete, I put the phone to my mouth and finished the recording with my own voice. When completed, my outgoing message consisted of two repetitions of “doo-dah-deet” followed by my voice inviting humans to leave a message if they want to.

But Does It Work?

I didn’t have to wait long to see if my idea would work. Forty-five minutes after modifying my outgoing message, T. Parasitus called again. I let my voice mail answer. “Doo-ha-deet” was played and that was it! After a particularly bad week in which I had been called no less than 14 times, I suddenly enjoyed an entire week of absolute silence!        

Over the last several weeks, I’ve still received a few isolated calls here and there, each time from a different number. These calls appear to be probing or exploratory in nature. Perhaps their system is making sure that what appears to be a “bad” phone number is truly bad, and not just temporarily out of commission. Or, my T. Parasitus may have sold or shared my number with other parasites. Either way, this present level of inconvenience is a tiny fraction of the call traffic I suffered when my infection was at its worst.

Given T. Parasitus' abrupt and dramatic change in behavior, I am persuaded that the intercept tones in my outgoing message have fooled the unwelcome auto-dialer callers. Evidence now suggests that if I leave “doo-dah-deet” in place long enough, Telephonium Parasitus calls will eventually wither away to nothing.


A week or so after publishing this article to my website, I was contacted by Jenn of  http://www.thisisarecording.com. Apparently she operates another website called  touchtonetunes.com. There you'll find the numerical sequences necessary to play dozens and dozens of well-known songs on a standard touchtone keypad.

Perhaps more to the point, she has also suffered at the hands of T. Parasitus and shared an amusing experience in which she used recorded touchtones to mess with a telemarketer's menu system.

One wonders how else this technique could be applied to combat telephone parasites.


(pilot 09/27/14)

(v2 10/07/14)