CallClerk - Settings - Call Blocking (How to block telemarketers / robocalls)

CallClerk blocks calls based on the caller id information provided by your phone company; either the caller id phone number or caller id name can be used to block a call.

To block calls, the Call Blocking feature needs to be turned 'ON' in the CallClerk - Settings - Control Panel window for Blocked Callers.

How CallClerk determines which calls to block

CallClerk determines how to block a call based on a variety of factors.

Directory entries:

First, its important to note that each call has associated with it a directory entry.   Directory entries are automatically generated for all new callers.    Each directory entry contains information that helps CallClerk determine how to block calls - this information includes the caller id data from your phone company as well as a CallClerk Caller Type.  For more information the CallClerk Directory click  here.

CallClerk Caller Types:

Call Blocking by Caller Type:

By default CallClerk's Call Blocking feature is turned on for 'Blocked' callers and off  for  'Familiar'  and 'Unfamiliar' callers. 

These setting can be changed on the  CallClerk - Settings - Control Panel window. 

Directory entries with caller types of  'Custom' allow all of CallClerk's feature, including Call Blocking, to be turned on or off  in any combination.

CallClerk determines if its going to block a call or not as follows:

1. When a call comes in, if CallClerk finds a directory entry exactly matching the caller's caller id number, CallClerk will use the caller type of the associated directory entry to determine if the call should be blocked.  

2. If there is no matching directory entry, CallClerk will look to see if you have any directory entries set up to handle calls with high level prefixes - for example for all 1-800 calls.   If such an entry is found, CallClerk will block the call based on the caller type of that templated entry.  For more information please click here.

3. If there is still no match, CallClerk will look to see if you have a Directory entry set up to handle calls with a specific name - for example all calls from "Doe, John" regardless of the number.   If such an entry is found, CallClerk will block the call based on the caller type of that templated entry.  For more information please click here.

4. If there is still no match and you are using CallClerk's Outlook integration feature, CallClerk will check to see if the caller's number can be found in your Outlook contact lists.   If a match is found CallClerk assigns an 'Unfamiliar' caller type.   Outlook entries can also be imported into the CallClerk directory, and the imported directory entries can have their caller types set to 'Familiar', 'Unfamiliar' or 'Blocked' through the import process.   If the Outlook entries are imported into the directory, their caller type in the directory will be used (point 1 above) rather than an 'Unfamiliar' caller type being used.

5. If there is still no match,  CallClerk will look in your personal Blacklists and Whitelists for names and numbers to determine if the call should be blocked.  CallClerk will block a call if it finds a matching entry in either your name and number Blacklist as long as that entry is not superseded by an entry in your Whitelists.   For example a Blacklisted Caller ID name entry that matches to the pattern "*Lawncare*" can be used to block any call that has a caller id name containing the word "Lawncare".   However if there is also a Whitelist entry for *Joes Lawncare* then calls from "Joes Lawncare" will not be blocked, but calls from "Raphs Lawncare" will be blocked.  CallClerk's Blacklist and Whitelist processing is described in more detail below.

6. If there is still no match, and if the caller id information is not covered by a Whitelist name or number entry, CallClerk can optionally also check the database of nuisance callers, as described in more detail below, to determine if the call should be blocked.

7. If there is still no match,  CallClerk will designate the call with a 'Unfamiliar' caller type and assuming you have 'Unfamiliar' calls set up with the Call Blocking feature turned off in the CallClerk - Settings - Control Panel, the call will not be blocked.

Note: As all new calls are generally assigned a default caller type of 'Unfamiliar' (expect in the situations detailed in points 2, 3, 5 and 6 above) setting the Call Blocking feature on for 'Unfamiliar' and 'Blocked' callers, and off for 'Familiar' callers, will effectively have CallClerk block all new calls except if they are in your Familiar list.


The above all happens very quickly

As soon as CallClerk gets the caller id info it starts to work on blocking your call as needed. 

In most countries the caller id information is normally delivered between the first and second ring - the U.S. and Canada are examples.   In these cases it means that you may hear your phone ring once before you phone company delivers the caller id information and before CallClerk can decide to block the call or not.

Also, even through checking the can take some time in some cases this can happen well within a couple seconds, and even in that situation the call can be blocked before the second ring.

However, in some countries phone companies deliver the caller id information before the first ring - the U.K. and Israel are examples.  In these cases you may not even hear the phone ring at all when a call is blocked.

What happens when a call is blocked

When CallClerk 'blocks a call' what it does is answers the call, optionally plays a Special Information Tone (SIT) and/or pre-recorded message and then hangs-up.

The SIT may fool some telemarketer's auto dial equipment into believing your line is disconnected.

You can use CallClerk's default pre-recorded message for blocked callers, which say "Please take this number off your calling list and do not call again, calls to this number are being logged.", or you may record your own.

Non voice modems, which can not play the SIT or the call blocking message, will simpy answer the line wait a few seconds and hang up.

Blacklists and Whitelists

CallClerk supports Blacklists and Whitelists for both CallerID Names and Numbers.  When CallClerk is deciding if it is going to block a call it looks at these lists.

To determine if a call is going to be blocked based on the Blacklists and White Lists the program checks:
1. The Caller ID Name from the phone company and the Caller ID Number from the phone company to see if there is a match in the blacklists.

Black lists for names can contain "*"s.   A "*" means any characters.  Example entries:
    Smith, John

Blacklists for number contain the leading digits of a phone number.  Example entries:

Note: some phone company's in North America will  require a 1 infront of long distance numbers. Example:

The call will then be blocked unless there is a Whitelist entry that overides at least one of the blacklisted entries

For example a Whitelist entry of  Joes Lawncare would override *Lawncare* for a call from Joes Lawncare but not one from Ralphs Lawncare.  

Also a Whitelist entry of 800555 would override a blacklist entry of 800 for the number 8005551234 but not for the number 8005561234. 

To add a new entry to a blacklist or whitelist, just enter it at the bottom of the list.
To edit an existing entry, just double click on the entry in the list and edit it.
To remove an entry, just double click on the entry in the list, delete all the numbers/characters for that entry, and then click anywhere else on the windows.

CallClerk automatically sorts entries in your blacklists and whitelists.

Blacklists and Whitelists can be imported and exported from the CallClerk - Blacklists and Whitelists window.   To get to this window just click the button entitled 'Update Blacklists and Whitelists' on the CallClerk - Settings - Call Blocking window.

Call blocking with the help of is an independent online service used by those who want to access and report information on nuisance callers.

CallClerk is designed to interface with to help identify calls to be automatically blocked. provides a score for nuisance callers based reporting from the community. Scoring in roughly translates into one point being applied for each unique person who reports the caller's number. CallClerk can also work with to determine scoring based on the number of calls reported in a particular time frame.

CallClerk works with this scoring system and your choices to automatically block a call, here's how ....

First, you need a (free) account from

Once you have your account, just enter your user id and password on the CallClerk - Settings - Call Blocking window. Please note: when setting up your password on the website please do not use any special characters in your password, that is to say please only use letters and numbers in your password.

After you have entered your account information just set the criteria at which new callers will be automatically blocked - for example a score of 2 in the last 90 days.

New callers will then be assessed and blocked based on the criteria you have set. When CallClerk blocks a call with the help of the CallClerk pop up window will appear in orange and the caller's call type will be set to 'Blocked'. If you don't see the orange pop up don't worry, as after that all calls from that number will be blocked (and the CallClerk pop up window will appear in red). To prevent the call from being blocked, simply change the caller's call type to 'familiar' or 'unfamiliar' in the CallClerk directory (assuming the Call Blocking feature is turned 'OFF' in the CallClerk control panel for those types of callers.

Reporting a caller to

You can report nuisance callers to with the help of CallClerk. This is done by either clicking the 'Block' button on the CallClerk Display Pop-up window, or by clicking on 'Edit - Report to' from the CallClerk - Directory or CallClerk History windows. When you do this you will be provided a confirmation window (example below) showing you the caller id information and allowing you to optionally enter 'who this really is' (if you feel the caller id name was not a good indication), as well as your comments about the caller/call.

You can optional identify your postal code in the CallClerk - Settings - Call Blocking window to have calls reported by you mapped on the service.

If you have already reported the caller's number to at least once before and the caller's number is tagged with a caller type of blocked, then subsequent calls from that number will be blocked and reported to automatically.   Please note, you need to report a caller's number to at least once before the subsequent calls from that same number will be automatically reported to   That is to say, if you block a call but have never reported it to before, subsequent calls from that number will not be automatically reported to

If  report of a nuisance caller to it will be publically viewable by the community. Your reporting will also be helpful to other CallClerk users using this service.

Call Blocking based on a match of Caller ID Name and Caller ID Number

Sometimes when telemarketers spoof their caller id information the Caller ID Name and Caller ID Number they use match.  CallClerk allows you to automatically block such calls.  In terms of matching, this means when the Caller ID Name and the Caller ID Number are either the same, or when either of the two has the digit "1" in front of it and the other does not.   For example, 5551234576 and 15551234567  are considered matches.

Of note, even with the option set to block calls when the Caller ID Name and Caller ID Number match, a caller can be overridden not to be blocked if it is already set up as an entry in the CallClerk Directory with a caller type of something other than ' Blocked' , or if either the name or number are defined in the CallClerk Whitelist.

When a call is blocked (automatically hung up on)

Options that can be set are:

1. Play Standard Intercept Tone (SIT) before hanging up. The SIT is a special sound used to identify numbers that are invalid, in some cases this will fool telemarketers auto dial systems into thinking your number is not valid.

2. Play a message before hanging-up.
If this option is checked CallClerk will play a message to the blocked caller before hanging up.

The first place CallClerk will look for the message to be played is the directory entry for the specific caller.

If no specific greeting exits CallClerk will play your personal default blocked message which you recorded or imported.

If you have not recorded or imported a personal default blocked message CallClerk will play a default message that says "Please take this number off your calling list and do not call again. Calls to this number are being logged.".

You can record your own default blocked message by clicking on the [Record] button (it will turn to a red [Stop] button), speaking into a microphone connected to your sound card, and then clicking on the red [Stop] button to end your recording.

You can also import a pre-recorded .wav file. To do this click on the [Import] button, find the file and click on OK.

Other Notes

These options can only be set if you are using a modem in TAPI mode. For more information please see the CallClerk - Settings - Modem window.

To test the above click on either of the test buttons.

Caller ID is delivered in some countries (such as the UK) before the first ring, and in others (such as the US and Canada) between the first and second ring. Once the caller id is provided by your phone company CallClerk will be able to immediately hang-up / block the call.

Once the current settings have been modified the changes may be permanently applied by clicking on the [Apply] or [OK] button or voided by clicking on the [Cancel] button. If either the [OK] or [Cancel] button is pressed then the CallClerk - Settings window will be hidden.

The CallClerk - Settings - Call Blocking and the Call Blocking Confirmation windows look like:

CallClerk - Settings - Call Blocking

CallClerk - Blacklists and Whitelists window

CallClerk - Call Blocking Confirmation window
Copyright 2004 - 2015 Rob Latour.  All Rights Reserved.
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