Filter Out Changing Spam Numbers

Automatically ignore batch spam numbers with Call Flow Designer

Written by Shelby Glynn
Updated over a week ago

This article provides an example setup you can use to filter changing spam numbers out of your main call flow, for cases when blocking individual numbers is not enough.

User Level:

  • Admin

Why do spam numbers keep changing?

Spoofed ID Spam Calls

Caller ID spoofing or number spoofing is a method commonly used with robocalls, wherein incoming spam numbers will look almost identical, but with the last four or five digits changed to make blocking more difficult and time consuming. We can redirect these spam calls out of the main queue using a condition splitter.

Filter Out Spam Calls with Condition Splitter

The condition splitter is a type of action available for Essential, Expert, and Custom plans within the call flow designer. Using a condition splitter is great for cases where a user wants to automate the filtering of incoming calls based on the call data.

In order to sort out these spam number patterns, we can set conditions which filter all incoming calls by their beginning digits.

Example Case:

A company is receiving an influx of spam calls that start with the same country codes and beginning digits. The last four digits of the incoming numbers change daily, making it impossible to preemptively block numbers.

Number patterns: [+420 887 78x xxx], [+420 778 87x xxx]


Recognize and reroute incoming spam calls to a separate branch where they will be automatically marked as resolved.


  1. Navigate to the Numbers tab from the lefthand sidebar and find the number which is being affected by spam calls, then click the blue pencil icon next to it.

  2. In our example, we want to add a condition splitter as the first step in our call flow, in order to remove certain numbers from the regular route. Click the blue + icon next to the number at the beginning of the call flow, and from the action types select Condition Splitter.

  3. Click Ok.

  4. Notice that our preexisting call branch has become a branch off of the Condition Splitter step. Since we are editing an existing call flow in this example, we can click the cog icon next to Condition Splitter.

  5. All we should do for this existing branch is to check the box labeled No other condition is met underneath Condition splitter settings. This will ensure all viable numbers can continue through our existing call flow normally.

  6. Now we must make some condition steps to filter for recognized spam numbers. In our example case, there are two possible patterns we want to look for, and we will make separate actions for each. Click the + icon to add a new action, selecting Mark call as resolved.

  7. Scroll to the Condition Splitter settings section. As a Property, we select Call - External number, which refers to the external or contact number calling in. For an operand, we can choose starts with. Type in the first spam pattern, without spaces. From our example, the first number would look like: +42088778.

  8. Once we have clicked Confirm and OK to save changes on the previous conditional branch, we must add one more conditional branch for the other spam-associated number prefix. Click the blue + icon and choose another Mark call as resolved action.

  9. Use the same type of condition as previously, with the Property > Call - External number and the Operand > Starts with. Type in the next number pattern with no spaces as a Value. Our example would look like: +42077887. Confirm condition settings, then click OK to finalize the action step.

  10. We have now created a call flow structure to automatically sort out numbers with known spam prefixes. From this point, we can add more action steps to our main call branch as necessary. At the end of the editing process, make sure to Save Plan via the green button at the bottom of the page.

Have more questions? Contact our Support team. We're always happy to help!

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