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# How to enable mask caller ID

**Mask Caller ID** controls what phone number appears on the agent's screen when an inbound call arrives. 
Instead of always showing the caller's real number, you can choose to display the tracking number, the destination number, or nothing at all (anonymous).
Use it to help agents instantly identify which campaign a call came from, or to protect caller privacy when sending leads to third-party clients on a pay-per-call model.

### Step 1. Open the Call Flow Builder

* Go to [Tracking > Call Flows](https://app.nimbata.com/tracking/call-flows).
* Click **Create** to start a new call flow, or click an existing call flow to add masking to it.

### Step 2. Add the Mask Caller ID action

* Click the **+** button under **New Call**.
* Select **Mask Caller ID** from the Add-ons menu.

![](https://storage.crisp.chat/users/helpdesk/website/-/2/f/4/5/2f459a49cf382400/image_7l4mbr.png)

### Step 3. Choose what to display on the agent's screen

Select one of the three options:
* **Show Anonymous Caller ID**: The agent sees no number (private/withheld).
* **Show Tracking Number as Caller ID**: The agent sees the tracking number the caller dialed.
* **Show Destination Number as Caller ID**: The agent sees their own destination number.

![](https://storage.crisp.chat/users/helpdesk/website/-/2/f/4/5/2f459a49cf382400/image_21d74z.png)

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🎉 Done. Incoming calls on this flow will display the caller ID you selected.
Detailed Guide: [**How to assign tracking numbers to call flows**](https://help.nimbata.com/en/article/how-to-assign-tracking-numbers-to-call-flows-uxu7qb/)