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We've all been driven to madness by one form of scammy telemarketer or another for years now. Seems like there's nothing we can do to avoid them.


For your mobile phone, there are apps that can warn you by showing "possible telemarketer" or something when your phone rings. I've always laughed at that. Why show that warning at all? Who among us will think "Hmmm... The phone says it might be a telemarketer. But hey, I'll answer anyway!" Um... No.

The FCC's Do Not Call list is a joke. I'm enrolled but it hasn't appeared to slow down the deluge of junk calls I get. The phone companies, wireless carriers, and congress obviously don't care or else they'd have done something long ago. e.g. Congress could pass legislation that mandated effective call blockers which would win widespread accolades. But they don't.

Even worse, some robocalls aren't subject to FCC do not call rules to begin with. Certain charities and political organizations, e.g. campaigning, are still allowed to place a certain number of calls per month whether you like it or not.

robot holding phone receiver

Caller ID-based blocking

Prior to just recently at the time of this writing (summer 2023), telemarketers could quite easily spoof caller ID -- making any name and number they want appear on your phone, sometimes even your own number. So relying on caller ID to identify a telemarketer was useless.

Because caller ID was useless then any blocking technology that relied on caller ID was also useless.

Thing have changed quite a bit on that front. A new technology called STIR/SHAKEN (🙄you just can't make this stuff up) introduces an authentication scheme for caller ID that's designed to make spoofing impossible. So you should no longer receive calls from telemarketers spoofing legit phone numbers. So far, so good.

But telemarketers are gonna telemarket. Now that caller ID spoofing is no longer so easy or possible, they are simply rotating between millions of unspoofed phone numbers. That means that telemarketers are, indeed, calling from the number that appears on your phone (so, no spoofing) but that hardly matters. The number still isn't tied directly to the telemarketer and they frequently change to a new number as the old ones land on block lists.

Over the past few months, an old phone number that I have parked (but don't use) attracted upward 30 to 50 calls per day(!) according to call logs, all from different phone numbers, advertising the same thing. In this case, federal relief money that I'm supposedly due. It attracted probably over a thousand robocalls that year, all from different phone numbers before I added the robocall blocker. So, yeah, calling number authentication hasn't eliminated telemarketers. It just made them change their methods. Cat and mouse.

Because I'm such a language pedant, let us define some terms here:

  • A "robocaller" uses an automated dialer to place the call. When you answer, the calling computer begins playing its prerecorded message. That's when you hang-up, mumble a curse, then go on about your business. The prerecorded message may offer to connect to a live agent after the message plays or it may simply hang up, depending on the needs of the company that's calling you.

  • A "robodialer", or auto-dialer, is similar, but all it does is dial phone numbers. When you answer, the call is quickly routed to the next available live agent, known in the biz as a closer, who takes over the call. That's the tell-tale pause you sometimes experience after answering but before you hear anything.

Robodialers are huge time savers for an operation with (live) closers because the closer doesn't have to manually dial, wait for an answer, and most likely get your voicemail. That's unproductive time. The call is dialed automatically then is passed to the closer only if the mark (that's you, heh heh) answers and the robodialer detects that you're human -- usually because humans say "hello" and quietly wait. Most robodialers know if your voicemail answers and will hang up or maybe play a message rather than pass the call to a closer, wasting their valuable time.

My method is 100% effective against robocallers and nearly so against robodialers as well.

Prove Thyself Worthy

"Challenge/Response" is a simple type of Reverse Turing Test (wut??) whereby a machine (a computer program) tries to figure out if it's communicating with a human or another machine. In this case, the "challenge" is issued by the machine (my robocaller killer) and the "response" is provided by the party being tested (the party that's calling me). A machine (robodialer) calling me will fail this test but a human calling me can easily pass it.

You actually see quite a lot of challenge/response systems today. Whenever you see a CAPTCHA*, you know, those things where you have to decipher a string of warped letters with squiggly lines or click on all the pictures that include a cat, well, that's a challenge/response system at work, trying to figure out if you're human or not. Web sites, especially on sign-up screens, use CAPTCHAs to avoid automated abuse. Much like what we'd like to use to avoid robocallers, if only we could. Well, it turns out we can.

* CAPTCHA : Completely Automated Public Turing test to tell Computers and Humans Apart.

Challenge/Response "puzzles" work remarkably well at separating humans from machines because the good ones are easy and fast for people to solve but very difficult for a computer to solve. That's the entire point and is basically what I did to eliminate robocallers.

My Robocall Blocker

What if you could install an app on your mobile phone that really works and eliminates the unwanted junk phone calls you receive? No warnings and no ringing. Robocallers are hung-up on without you ever knowing except that your phone will be curiously quieter than it used to be.

There's a low cost VoIP (Voice over IP) phone service called MagicJack. They got their start in the mid-aughts offering alternative low cost landline telephone service. They still do today. But they also offer a mobile phone app that lets you place and receive calls with a second phone number.

But here's the real value: MagicJack (MJ) has a robocaller blocker that uses the challenge/response method discussed above. When that feature is enabled (it's optional but free), then all incoming calls to your MJ phone number will play a message to the caller saying the following:

"The number you are trying to reach has automatic call screening service. To reach the called party please press n."


The number n is a random one-digit number that changes with each incoming call.

If the caller is a robocaller then it's highly unlikely it'll be able to perform the required number press. And without it the call will be dropped after a few seconds without ringing my phone.

What makes this so elegant and superior is its simplicity for the caller. They don't have to announce themselves, as if requesting an audience with the pope, as some call screening systems require and I'm not presenting them with an aggravating list of options like you'd hear when calling most large companies. And since everyone can get behind the effort to reduce robocalls then callers should not mind the simple "touch the number" request.

Potential Downsides

Unfortunately, the MJ blocker I'm using doesn't allow me to whitelist callers in my contacts. Everyone hears the "touch a number" message no matter who they are. But that's a tiny price to pay, in my opinion, to avoid a ton of robocallers.


If you rely on certain legitimate automated callers to give you info, like maybe your kid's school is cancelled due to weather, your prescription meds are ready to pick up, or some such, this system will interfere with that. Those legitimate info-only robocalling systems cannot understand the "touch a number" message so they'll never be able to ring through to you.

But I don't think this is such a big problem these days. Most legit organizations that need to reach you or broadcast an important message can be configured to send a text message, which this blocking system doesn't touch. The days of voice-based info announcements are waning, thankfully. Text messages are the best way to receive such notices anyway.

How do I set it up?

There's a number of steps to setting this system up and may be a bit over the top for some non-geeks. There's also an ongoing cost which is pretty cheap at about $4/month. To me, that's a tiny price to pay for a very-nearly 100% effective robocall blocker considering that otherwise I might receive a several dozen robocalls in a given month.

Here's what happens when someone calls me:

  • A person calling my main number (mobile) is immediately forwarded to the MJ phone number. This is invisible to the caller.

  • MJ answers the call then plays the message asking the caller to touch the correct number.

  • If the caller complies then proceed with the next point below. If not, the caller is hung-up on and that's it.

  • The MJ app on my mobile phone rings. I see the caller ID or contact name as usual.

  • If I answer, then we talk. Then I'll hang up when we're done. Nothing different there.

  • If I don't answer, the call is routed to voicemail that plays my greeting, like any regular voicemail.

As I stated above, the only thing different that a caller encounters using this system is the brief "touch a number" message. That's it. And since I can be more confident that a ring-through is a real human, even from numbers marked "unknown", then I'll answer. And my blood pressure doesn't go up!

Telemarketer Bypass? It's possible that a live caller may hear the "touch a number" request and comply. I've had 2-3 of those in the past few years so I'm not too concerned. But that's pretty rare nowadays. Most junk callers use robocallers that play a prerecorded message. Closer hand-offs, if any, probably come at the end or if I would touch a number for more info (which of course I never do). Secondly, robodialers can dump a call that is answered by a non-human (like my touch a number message) especially if the robodialer was designed to hand off the call to a closer.

If you don't mind paying a few bucks a month to pretty much eliminate junk calls then you might like this solution. If you want me to set up something like this for you, then give me a call (or text or email). My contact info is on the home page.

There's also a landline cordless phone system that can do the same thing. VTECH makes a cordless phone system that includes a call blocking feature that works similarly to above and it'll work with any land line based phone provider. Callers to your landline are quietly answered by the base station and asked to touch "#" to ring through. If the caller doesn't touch # then the call is dropped -- all without disruptive ringing.

Here's a link to for the VTECH phone system.

Alas, as A.I. powered voice recognition systems mature, my fix may one day become obsolete. But for now anyway, it works.

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