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. 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 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 is available on Essential, Expert, and Custom plans. 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.
Calls matching either spam prefix are now automatically marked as resolved and never reach your agents. All other calls flow through normally.
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.
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