This is the Technical Data portion of The Telemarketing Scum Page. I pretty much ignored this stuff until I discovered how to completely stay off their lists (meaning two months of no calls at the time of this writing, 3-99).

Strategies for Staying Off their Lists

The Federal "Do Not Call" List (US) is an obvious place to start.

Get on their blacklist.

When the scum find out that you are costing them money, they have a choice:

1. Put you on their "call back" list. That should discourage "non-cooperating" victims, but it also greatly increases their costs. So they simply don't do this.
2. Blacklist you. That way your number must come off all of their lists.

Remember there's a basic difference between being "deleted", meaning "deleted from a database" on a particular sales campaign, and being blacklisted, meaning "invalid for calling". You want to be blacklisted and therefore removed from the master database.

Avoid getting on their lists.

Get on a "Do Not Call" list for all major telemarketing companies.

... as distinguished from the scum who use telemarketing companies. It may also be possible to cover most major businesses that use telemarketing companies, but it makes more sense to identify the actual telemarketing companies.

Block telemarketing calls.

  Blocking Telemarketing Calls

Have your answering machine provide messages in a non-standard format.

This can be very effective. This is described in detail at www.scn.org/~bk269/bug.html. Briefly, telemarketing scum intentionally hang up on answering machines. So the idea is to confuse the answering machine detection equipment.

Screen calls with an answering machine but tell callers that if you're home, you will pick up the phone on hearing a voice.

Some answering machines sold by Radio Shack and others offer a 3 digit bypass codes for the purpose, so regular callers don't need to listen to your stupid machine. (This is called a "breakthrough device".) Telemarketing scum usually don't leave messages and don't even have a human connected to a phone until after their "answering machine detection" pause.

Simple Screening

... using a real answering machine or caller ID. This is the simplest solution and takes 3-5 attempts per campaign and perhaps 5-10 attempts per telescum operation. It is described on the main Telemarketing Scum Page.

Don't use a "voice messaging" service which provides an initial tone.

The tone can be used by telemarketing scum to avoid LD charges and make it practical to "hammer" on the answering service until they get through. (Don't confuse a simple tone with SIT tones. SIT tones are very useful.)

If you subscribe to a voice messaging service:

1. Make sure there is no initial tone.
2. Make sure you can screen calls as they come in. Most "voice messaging" services don't allow that, but cheap machines can be had for the price of 4 months' "voice messaging" service.

Don't answer "hello" twice.

If your friends are dialing with a secondary device (speakerphone as a dialer, cell phone dialer, etc.), they will know they could have missed your "hello" and say, "hello" themselves.

It appears that almost all predictive dialers will register a single "hello" as an invalid number. In those cases, you should get about three attempts, followed by removal from that company's master list.

If you get a large number of telescum calls, use a SIT tone at the beginning of your answering machine message.

SIT tones include intercept tones, busy signals, reorder busy signals, etc. Predictive dialers delete numbers with certain types of SIT tones. (Disconnected number is a good one.) Here's a sample (15k) and a digitally synthesized (45k) sample so you don't have to go to Napster. Here's "Dude's" version.

Anecdotal reports are that the first beep controls predictive dialer response. This contradicts Dialogic's literature, but nevertheless appears to work.

It is possible to purchase a device which adds SIT tones.

Better yet, if you don't mind spending money for caller ID, it is possible to purchase an answering machine with a caller ID intercept feature.

  Staying off their Lists

Never give a valid home phone number to a commercial entity unless you absolutely trust that entity. The Federal Telemarketing Rule has an "existing business relationship" exception to the Federal "Do Not Call" list.
Options:

1. work phone - easy to reach you when necessary and usually dead at the dinner hour
2. "Unlisted."   "I can't be reached at home during business hours anyway."
3. a payphone that accepts incoming calls. (If it's indoors, be judicious.) (list of payphones here or search for <payphone list>)
   
   Keep a couple of these numbers in your wallet!
4. an ISP's modem huntgroup number - make sure it's a toll call.
5. a live number for a local telemarketer
6. a fax machine
7. a commercial number with an answering machine
8. a random commercial number (xxx-3000; This is a last resort.)

You'll have to look in your wallet for the chosen number, but you can always explain that you have a new number.

Make sure you have Caller ID block. (This is for outgoing calls; most incoming blocked calls are from individuals, whereas telescum typically have some sort of identifier or listed as "unavailable". Note that some telescum deliberately state "unavailable" as their name but do include a telephone number.)

Dial 800 numbers from a fax or data line. (Caller ID block doesn't typically work with 800 numbers.)

If you have unmetered long distance, use the number for overseas callers to a large business, if available. These often get "priority" response and it's generally possibly to block your number to these numbers (*67+1+number).

Don't use voice messaging services which use an initial tone.

This always tells the telemarketer when an answering machine has been reached, and may even permit them to avoid toll if they disconnect in time.

Avoid voicemail services which permit a caller to automatically bypass the ring

BellCanada had this system and a telemarketer was able to bypass the Canadian telemarketing law by avoiding ringing of victims' phones. (This seems to only be an issue where the bypass procedure is standardised or reached through a standard "gateway" number.)

I don't know the legal status of no-ring voicemail messages in the US, but this hasn't been reported yet.

Call Progress Detection

This is an extension of the technology that allows an answering machine to detect when a caller has hung up, and whether the caller has left a message. When used with "predictive dialer" software it determines whether a live human is on the line.

The procedure is to:

1. Make the call
2. Detect an answer.
3. "Answering Machine Detection"
4. Attempting to detect commercial establishments by length of greeting
5. Initiate the conversation by machine (not done yet, but it's just a matter of time)
6. Connect the call to an agent (the flunky)
7. Determine and log call completion.

Detecting an answer is accomplished by one of:

• detecting a ringback signal which is shorter than the first ringback signal. ("ringback" is the "phone ringing" noise the caller hears. In electronic exchanges, ringback is artificially produced and not synchronised with the ringing signal.)
• detecting a termination of ringback signals
• detecting voice
• detecting an answered call by "click detection"
• detecting a SIT signal indicating a connection.

The following is a .wav file for an invalid number SIT tone: errorbeeps1.wav (15k), from www.thisisarecording.com If it doesn't play clearly directly from the net, try downloading it. Or maybe Napster has it. Here's a digitally synthesized (45k) sample.

An "Intercept SIT tone is what you initially hear when you reach a North American number which is out of service or otherwise invalid.

I do not know the implications of producing a false intercept SIT tone, if the purpose is discouraging telemarketing scum. According to a PacBell customer agent, their anti-fraud people do not consider false SIT tones a problem. The purpose of the tones is to notify computerised dialers of the call outcome. So I'd say check with your local telephone company first just to make sure it's not a violation of the Official Secrets Act or something. It is my understanding that toll charges are determined by a "supervisory channel" and NOT by the SIT tones. If that is true in all cases, abuse of these SIT tones should be okay.

This is not a phone phreaking site, but search of "2600" will turn up plenty of legal and illegal stuff for the curious.

The above was of course written before the introduction of the Zapper. There's one patent I should have filed!

Predictive dialers use the SIT intercept tone to identify an invalid number.

Answering Machine Detection

"Answering machine detection" is part of "call outcome detection". This is the weak point in their software. "Answering machine detection" takes time and depends on predicting responses of the answering machine and of live victims.

If an answering machine is detected, the predictive dialing software will call the number back later. It seems that they make between 3 and 10 attempts, but an extended campaign may include more attempts made at a later time.

If you can defeat this process, you've pretty much defeated the entire "call outcome detection" software.

Duration of Hello

1.7 sec. - residence

2-4 seconds - business

So what if you answer as, "Hello. Clinton residence." or "Hello. Monica Speaking.", or if your business calls are answered with just the company name? I suspect that this feature of call progress detection is usually turned off.

From Dialogic Corp.:

"After Call Progress Analysis is complete, check ansrsize. If ansrsize is less than 180 (1.8 seconds), you have probably contacted a residence. An ansrsize value of 180 to 300 (1.8 and 3.0) is probably a business. If ansrsize is larger than 480, you have probably contacted (sic.) an answering machine. An ansrsize value of 0 means that a connect event was returned because excessive silence was detected."

Connecting to the Agent

Since this follows Answering Machine Detection, you can expect either a pause or (in the future) a mechanical response while Answering Machine Detection continues.

Usually this follows a pause.

So if you hear that pause, just don't repeat your "hello" unless you want to engage these a__holes. That should automatically remove your number from all of their lists.

Alternative responses include no further response, tapping on the receiver, etc.

Obsolete Techniques (not very useful)

Telemarketing equipment manufacturers have largely abandoned techniques used to detect tape hiss from answering machines and dropouts from digital machines. There are too many variables resulting from signal processing techniques used by the carriers for automated detection to be viable. While more detailed raw signal analysis is possible, this would have to take into account a variety of voice processors used in both home machines and by the carriers for call handling.

The Casio (Casio Phonemate) TA-140/TA-145 has a "caller ID screening" feature. This could be set to divert "unavailable" calls. The Federal Telemarketing Rule now requires telemarketers to use caller ID, so this is no longer effective in screening calls. This device may have some limited use in outside of the US.

(This page will by Y2K compliant by 1st quarter, 1901.)

What to Expect

• Software which will initiate telemarketing calls with pre-recorded vocalizations. This is illegal in many states, but since when did telemarketing scum worry about that little detail? This will allow answering machine detection to proceed over a longer time period, so it will be necessary to extend anti-predictive dialer techniques accordingly.
• Voice recognition software - The answering machine detection may attempt to use standard phrases to identify answering machines.
• Phasar torpedos which can be fired at will at telemarketers
• And maybe even a good programmable telephone answering application which will run on Linux (Redhat 9.2 or later)

What to Look For

• Telephone answering software which will respond to vocalizations. - So when the telemarketers implement pre-recorded vocalizations, your machine will answer and eventually connect the machine to a live telemarketer. Meanwhile you can pick up the phone if you accidentally snag a real human being (as opposed to a telemarketer).
• Other call type detection equipment.
• Supervisory channel interrogation at the subscriber level.
• The phasar torpedos

Predictive Dialers and Answering Machine Detection

The scumballs who make predictive dialers do not like to disclose their techniques for "call progress detection". The information is nevertheless readily available by looking at sample patents:

Telemarketing Terms

Call Glossary from www.telanet.com/callglos.html

- more on call outcome types and other telemarketing terms (target link) - some of these are for specific types of calls, including such things as customer service call back service, but this will give you an idea of the sort of thing they base their "business" practices on.

Telecommunications