> ## Documentation Index
> Fetch the complete documentation index at: https://help.cloudtalk.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Filter Out Changing Spam Numbers

> Automatically ignore batch spam numbers with Call Flow Designer

> [!NOTE]
>
> 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](/en/articles/2145423-blacklist-a-number) 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. Incoming spam numbers look almost identical, but the last four or five digits change to make blocking more difficult and time-consuming. Since you can't preemptively block numbers that don't exist yet, [blocking individual numbers](/en/articles/2145423-blacklist-a-number) isn't enough. Instead, you can use a Condition Splitter to redirect calls matching a spam pattern out of your main queue.

## Filter Out Spam Calls with Condition Splitter

The [Condition Splitter](/en/articles/5763009-caller-based-routing-with-conditions) is available on [Essential, Expert, and Custom plans](https://www.cloudtalk.io/pricing). It lets you filter incoming calls based on their number patterns, so calls matching known spam prefixes are automatically routed away from your agents.

**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 change daily, making it impossible to block them one by one.

Spam number patterns**:** `+420 887 78x xxx`, `+420 778 87x xxx`

**Goal**: Recognize and reroute incoming spam calls to a separate branch where they are automatically marked as resolved, so agents know no callback is needed.

### **Steps**

1\. From the **Dashboard**, click **Numbers**.

2\. In the **My numbers** tab, find the number being affected by spam calls.

3\. Click **+ Configure** (or the flow name, if one exists) in the **Call Flow** column.

4\. On the canvas, click the **`+`** button at the beginning of the flow and add a **Condition Splitter** from the step library (under **Routing logic**).

5\. Click the Condition Splitter step to open its config panel. Check **No other condition is met** and click **Save**. This creates a fallback branch where all legitimate calls will continue through the normal flow.

6\. Click the Condition Splitter step again. Click **Add new** and set the first spam pattern condition:

* **Property**: Call - External number

* **Operand**: starts with

* **Value**: +42088778

7\. Click **Confirm**.

8\. Click the Condition Splitter step again, click **Add new** and set the second spam pattern:

* **Property**: Call - External number

* **Operand**: starts with

* **Value**: +42077887

9\. Click **Confirm**, then **Save**.

10\. On the canvas, each spam pattern now has its own branch. Click the **`+`** button below each spam branch and add a **Mark Call as Resolved** step. This automatically closes the call so agents see it marked as resolved (no callback needed).

11\. On the **No other condition is met** branch, add your normal call flow steps (Greeting, Ring to, Voicemail, etc.).

12\. Click **Save** in the top-right corner to make your flow live.

![](https://mintcdn.com/cloudtalk/Cdyt2I6w7OABieBC/images/help-center/articles/5810641/fe98f2f6f70f-screenshot-2026-08-18-at-10-59-48.png?fit=max\&auto=format\&n=Cdyt2I6w7OABieBC\&q=85\&s=55a0c8029b7db88e530dd90dc0ee861a)

Calls matching either spam prefix are now automatically marked as resolved and never reach your agents. All other calls flow through normally.

> [!WARNING]
>
> **Quick Tip:** Do you know the full phone numbers of the spam callers? Use CloudTalk's **Blacklist** feature to block these numbers for inbound, outbound, or both types of calls. For more details, see the [Blacklist documentation](/en/articles/2145423-blacklist-a-number).

***

*Need help or have a question?* Just reach out through our [Support portal](https://support.cloudtalk.io/hc/en-us/requests/new?ticket_form_id=26305535257884) — we’re here for you.


## Related topics

- [Routing & Call Flow Design guide](/en/articles/10559796-routing-call-flow-design-guide.md)
- [Local Calling in Brazil: Blocked or Filtered Calls to Vivo Numbers](/en/articles/16630561-local-calling-in-brazil-blocked-or-filtered-calls-to-vivo-numbers.md)
- [Numeracle Add-On: USA Number Reputation and Spam Management](/en/articles/11461699-numeracle-add-on-usa-number-reputation-and-spam-management.md)


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