The most effective way to reduce telemarketing calls is to get placed on a state's "No Call List" if one is available in your area (see Dann's writeup above). However in many states there isn't such a list kept and in others there is a delay of 3 months to 1 year before telemarketers are required to quit calling.

There are a few products you can purchase that help you reduce these annoying calls, but they each have their limitations. The most effective products are the ones that utilize the Caller ID features of your phone. You might be tempted to try out some of these products so I have included information about all of them below:

The TeleZapper and other devices utilizing SIT tones

The TeleZapper is a heavily advertised product that promises to greatly reduce the frequency of telemarketing calls. The product is manufactured by Privacy Technologies Inc., a wholly owned subsidiary of Royal Appliance Mfg. Co. (The people behind the Dirt Devil and Royal Vacuum Sweepers. The first TeleZapper model was introduced into national retail stores in the fall of 2001. A new version introduced in 2002 eliminated the electrical cord and bulky AC adapter (by using batteries) and it also allows selection between one (Basic Privacy) to three tones (Advanced Privacy). The current version has a suggested retail price of $39.99.

How does the TeleZapper work?

The TeleZapper plugs into your phone line. When a phone line is picked up by either a human or an answering machine it detects the voltage drop in the line and emits either a single tone or a series of three tones. The three tones are called SIT tones and they are very familar to people that have dialed a non-existant number. It sounds something like "duh...doo...dah". Normally the telephone company follows the SIT tones with an informational message, e.g. "The number you are trying to reach is no longer in service."

The single-tone ("Basic Privacy") option uses just the first of the three tones. Many dialers will disconnect upon hearing just the single tone, while others require all three.

If the telemarketer is using an affected predictive dialer their computer will hear the tones and hang up. Some dialers will disconnect on the first tone and others apparently require all three. The dial may also remove the number from the dialers call list depending on how it was programmed. If your number is removed from the call list you won't receive any more calls from that telemarketer.

Royal claims the TeleZapper eliminates ~90% of the telemarketing calls to a phone line after being used for just one month. Independent anecdotal evidence indicates that the rate is not nearly that high but most people say that the product does work to some extent in lowering the number of calls. The major deficiency of the product is that it is completely ineffective unless the person is using predictive dialing. About 20% of telemarketers don't use any computerized dialers and they will still get through.

You should be aware that every caller to your house will hear these tones when you pick up the phone. They might even be confused and hang up. You might get annoyed having to explain the odd tones to every caller. Also, there are some organizations that use predictive dialers that you may actually want to hear from: blood banks, doctor's office, or your church. Reminder calls from your favorite organizations may be dropped.

Isn't forty bucks a little high for a tone player?

Yes it is. You can easily make a similar device using your own answering machine. All you need to do is record the proper SIT tones before your outgoing message on your machine. There are 4 different SIT tones available, but the TeleZapper and similar products all use the tone that specifies "Vacant Circuit (out of service or nonexistent phone number)".

You can download the proper SIT tones from numerous sources on the internet. Just do a search for "SIT tones" on and you'll quickly find a site that has them. At least for now you can download all the SIT Tones from:

Of course if you use your own answering machine to play the tones you'll have to let it screen all of your calls for a while. ("2002.11.16@15:36 yerricde says ...this won't work on some digital answering machines, as they are designed only for voice and don't pass pure tones properly. My Uniden answering machine has this feature".)

What are telemarketers doing about this?

Many of them have either altered or completed changed their "predictive dialer" programs so that they ignore the SIT tones. Avaya Inc., a company that makes dialer equipment has this to say about its newest dialer:

After extensive testing, results showed that the Mosaix Predictive Dialing System does not respond to this tone and operation after receiving the tone proceeds as if the tone was not there.

The TeleZapper has absolutely no effect on the operation of the Mosaix Predictive Dialing System.

As soon as telemarketers change their dialers to ignore SIT tones your $40 TeleZapper will be turned into a paperweight.

Answering machines with Caller ID Intercept or a Mailboxing Telephone Answering Machine

Most telemarketers come across as "Anonymous", "Unavailable", "Out-of-Area", or "Private" on Caller ID devices. There are products available that can immediately direct these calls to an answering machine device for screening. The answering machine can further eliminate calls by having SIT Tones played at the beginning of the message.

Your phone will ring normally when someone calls supplying their Caller ID information and you can just pick it up if you choose. Some telemarketers supply their Caller ID information and come across normally but you should be able to recognize them from this information and just allow your answering machine to answer the calls.

Two of these products are the Casio Phonemate TA-140 (and TA-145) and Nortel Meridian M-9516 12 Box Caller ID Phone. These products aren't cheap. You'll pay around $150 for either one of them.

The Privacy Manager service offered by my local telco

SBC offers a subscription service for $5/month that directs all "Anonymous", "Unavailable", "Out-of-Area", or "Private" Caller ID calls to a voice messaging prompt system. Callers will hear a message that says:

"The person you are trying to reach does not accept unidentified calls. Your Caller ID was not received. To enter an access code, press 1. Or, to record your name so that we may announce your call, press 2."

If the caller enters the correct access code your phone will ring normally. If they record their name "Privacy Manager" will come across on the CallerID box and your phone will ring. If you answer it you'll get 4 options:

  1. Accept the call
  2. Reject the call: "The person you are calling is not available at this time. Please try again later."
  3. Send the call to CallNotes or an answering device.
  4. Send a solicitor's rejection: "Attention! Phone solicitors - Please add this person's name and telephone number to your Do Not Call list. The person you are calling does not accept phone solicitations."

Boxes that have you push a button when you hear a telemarketer

There are many devices offered where you must press a button after you notice you have a live telemarketer on the other end of your phone line. When the button is pressed a recorded message tells the person on the other end that you want to be removed from their call list and you don't want any further calls from them. This device is effective at stopping the live calls you pick up, but it won't stop them from filling up your answering machine with a sales pitch. It also won't stop recorded message sales pitches.