# Block a phone number

**Scenario:** A customer service agent reports that **15551234567** is making repeated nuisance calls and should be
blocked.

## Step 1: Create a Number List

1. Go to **Voice > Inbound Trunks** and open the **Number Lists** tab.
2. Click **Create New** and enter a **Friendly name** (e.g., *Number Blocklist*).
3. Set the **Mode** to **Full number match**.
4. Set the **Default action** to **Allow call**.
5. Click **Create**.

[![Creating a Number List for Blocking Specific Numbers](../../../../_images/example2_create.png)](../../../../_images/example2_create.png)


**Fig. 1.** Creating a Number List for Blocking Specific Numbers

## Step 2: Add the number to the list

Enter the number in the format used for matching. For a SIP trunk, use the calling-number format produced by the trunk's
**CLI Format** and **CLI Prefix** settings.

1. Click the **Actions** button next to the **Number List**.
2. Select **Manage numbers**.
3. Click **Add Numbers**.
4. Enter **15551234567** in the input field and set the action to **Reject call**.
5. Click **Submit**.

With **Full number match**, only a calling number identical to **15551234567** is rejected. Longer or shorter numbers
that contain these digits, such as **155512345678**, are not matched.

[![Adding a Number to Block Calls](../../../../_images/fig109.png)](../../../../_images/fig109.png)


**Fig. 2.** Adding a Number to Block Calls

## Step 3: Assign the Number List to a trunk

Assign the **Number List** to the inbound **SIP** or **PSTN** trunk that receives these calls so the call filtering
rules take effect. Select it in the trunk's **CLI Number List** field on the **Number Translations** tab. For the steps,
see [Assign a Number List to a Trunk](../how-to-guides/configure-number-lists.html#inbound-number-lists-assign).

Calls from **15551234567** are rejected, and all other calls follow the **Default action** and are allowed.

## Related resources

- [Number lists](../index.html) - Understand how Number Lists match calls and
  allow or reject them.
- [Configure number lists](../how-to-guides/configure-number-lists.html) -
  Create a Number List, add numbers or prefixes, and assign it to a trunk.
- [Number List settings reference](../number-list-settings-reference.html) -
  Look up field definitions, defaults, values, and limits.

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