# Number List Examples & Use Cases

This section provides real-world examples of how to use **Number Lists** to manage inbound call filtering. You'll learn
how to add numbers and set rules to allow or block calls based on specific criteria.

With **Number Lists**, you can:

> - **Block unwanted calls** from specific prefixes or numbers.
> - **Allow calls** from specific prefixes or numbers, while blocking all other calls.
> - **Load Balance** your traffic based on the incoming CLI.

Choose one of the following examples:

**1. Block Calls from a Specific Prefix**

Learn how to create a number list, which blocks calls from a specific prefix.

[Example 1: Block Calls from a Specific Prefix](#user-panel-voice-in-numberlist-examples-block-prefix)

**2. Block a Specific Phone Number**

Learn how to create a number list, which blocks calls from a specific phone number.

[Example 2: Block a Specific Phone Number](#user-panel-voice-in-numberlist-examples-block-number)

**3. Allow Calls from Specific Countries and Block Others**

Learn how to create a number list, which allows calls from a specific prefix, but blocks others.

[Example 3: Allow Calls from Specific Countries and Block Others](#user-panel-voice-in-numberlist-examples-allow)

**4. Use Number Lists for Load Balancing**

Learn how to use number lists as a load balancing tool for different SIP endpoints.

[Example 4: Use Number Lists for Load Balancing](#user-panel-voice-in-numberlist-examples-lb)

Note

After setting up your **Number List**, make sure to **assign it to an Inbound SIP Trunk** so the call filtering rules
take effect. For more details, see the [Assign a Number List to a SIP
Trunk](number-lists.html#user-panel-voice-in-numberlist-assign) guide.

---



## Example 1: Block Calls from a Specific Prefix

**Scenario:** A company receives frequent spam calls from numbers starting with **1234**, disrupting operations. To
block these calls follow the steps:

### Step 1: Create a Number List

> 1. Navigate to **Inbound Trunks > Number Lists**.
> 2. Click **Create New** and enter a **friendly name** (e.g., *Spam Blocklist*).
> 3. Set the **Mode** to **Prefix Match**.
> 4. Set the **Default Action** to **Allow Call**.
> 5. Click **Create**.
>
> [![Creating a Number List](../../_images/fig722.png)](../../_images/fig722.png)
>
>
> **Fig. 1.** Creating a Number List

### Step 2: Add the Prefix to the Number List

> 1. Click the [![Actions button](../../_images/three_dots_action_button1.png)](../../_images/three_dots_action_button1.png)
>    button next to the newly created **Number List**.
> 2. Select **Manage Numbers**.
> 3. Click **Add Numbers**.
> 4. Enter **1234** in the input field (this blocks all calls starting with **1234**) and set the action to **Reject Call**.
> 5. Click **Submit**.
>
> [![Adding a Prefix to Block Calls](../../_images/fig815.png)](../../_images/fig815.png)
>
>
> **Fig. 2.** Adding a Prefix to Block Calls

---

## Example 2: Block a Specific 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. Navigate to **Inbound Trunks > Number Lists**.
> 2. Click **Create New** and enter a **friendly name** (e.g., *Number Blocklist*).
> 3. Set the **Mode** to **Full Numbers 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. 3.** Creating a Number List for Blocking Specific Numbers

### Step 2: Add the Number to the List

> 1. Click the [![Actions button](../../_images/three_dots_action_button1.png)](../../_images/three_dots_action_button1.png)
>    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**.
>
> [![Adding a Number to Block Calls](../../_images/fig109.png)](../../_images/fig109.png)
>
>
> **Fig. 4.** Adding a Number to Block Calls

---

## Example 3: Allow Calls from Specific Countries and Block Others

**Scenario:** A company wants to accept calls only from **UK-based (44)** and **German (49)** customers while blocking
all other inbound calls.

### Step 1: Create a Number List

> 1. Navigate to **Inbound Trunks > Number Lists**.
> 2. Click **Create New** and enter a **friendly name** (e.g., *UK & Germany Only*).
> 3. Set the **Mode** to **Prefix Match**.
> 4. Set the **Default Action** to **Reject Call**.
> 5. Click **Create**.
>
> [![Creating a Number List for Country-Based Filtering](../../_images/fig1114.png)](../../_images/fig1114.png)
>
>
> **Fig. 5.** Creating a Number List for Country-Based Filtering

### Step 2: Add the Allowed Prefixes

> 1. Click the [![Actions button](../../_images/three_dots_action_button1.png)](../../_images/three_dots_action_button1.png)
>    button next to the **Number List**.
> 2. Select **Manage Numbers**.
> 3. Click **Add Numbers**.
> 4. Enter **44, 49** in the input field (this allows calls from the UK and Germany) and set the action to **Allow Call**.
> 5. Click **Submit**.
>
> [![Adding Country Codes to Allow Calls](../../_images/fig1215.png)](../../_images/fig1215.png)
>
>
> **Fig. 6.** Adding Country Codes to Allow Calls

---

## Example 4: Use Number Lists for Load Balancing

**Scenario:** A global service provider needs to route incoming calls based on the caller's country code (CLI prefix),
while using a single DID number.

**Solution:** To manage this, the provider assigns specific number lists to trunks within a trunk group. The system uses
the CLI prefix to match the call to the correct number list and selects the appropriate trunk for routing.

For example:

> - Calls from the United States (prefix `1`) are routed to a US-based trunk.
> - Calls from the United Kingdom (prefix `44`) are routed to a UK-based trunk.

This setup enables efficient load balancing and region-specific routing while maintaining a single DID.

### Step 1: Create Number Lists

> 1. Go to **Inbound Trunks > Number Lists**.
> 2. Click **Create New** and enter a **friendly name** (e.g., *US Source Filter*).
> 3. Set the **Mode** to **Prefix Match**.
> 4. Set the **Default Action** to **Reject Call**.
> 5. Click **Create**.
>
> [![Creating a Number List for Load Balancing - US](../../_images/fig1e4.png)](../../_images/fig1e4.png)
>
>
> **Fig. 7.** Creating a Number List for Load Balancing (US)
>
> 6. Click the [![Actions button](../../_images/three_dots_action_button1.png)](../../_images/three_dots_action_button1.png)
>    button next to the **US Source Filter** Number List.
> 7. Select **Manage Numbers**.
> 8. Click **Add Numbers**.
> 9. Enter **1** and set the action to **Allow Call**.
> 10. Click **Submit**.
>
> [![Adding US Prefix](../../_images/fig2e4.png)](../../_images/fig2e4.png)
>
>
> **Fig. 8.** Adding 1 Prefix for US
>
> 11. Repeat the steps above to create a second list named *UK Source Filter* and add prefix **44**.
>
> [![UK and US Source Filter Number Lists](../../_images/fig3e4.png)](../../_images/fig3e4.png)
>
>
> **Fig. 9.** UK and US Source Filter Number Lists

### Step 2: Assign Number Lists to Trunks

To assign the number lists to trunks see the [Assign a Number List to a SIP
Trunk](number-lists.html#user-panel-voice-in-numberlist-assign) guide or follow these steps:

> 1. Go to **Voice > Inbound Trunks**
> 2. Edit an existing trunk or [create a new trunk](creating-a-new-sip-trunk.html#user-panel-sipin-trunk).
> 3. Open the **Number Translations** tab and locate **CLI Number List**.
> 4. Select the **Number List** you want to assign and click **Submit** to save the changes.
> 5. Repeat the steps above for both trunks.
>
> [![Assign the Number Lists to Trunks](../../_images/fig4e4.png)](../../_images/fig4e4.png)
>
>
> **Fig. 10.** Assign the Number Lists to Trunks

### Step 3: Create a Trunk Group

To create a trunk group see the [create a trunk group](creating-a-new-trunk-group.html#user-panel-trunk-group) guide or
follow these steps:

> 1. Go to **Voice > Inbound Trunks**.
> 2. Click **Create New** and select **Trunk Group**.
> 3. Enter the trunk group **Name**.
> 4. In **Trunks**, add **US SIP Trunk** and **UK SIP Trunk**, then click **Create**.
>
> [![Create a Trunk Group](../../_images/fig5e4.png)](../../_images/fig5e4.png)
>
>
> **Fig. 11.** Create a Trunk Group.

### Step 4: Assign the Trunk Group to a DID Number

> 1. Navigate to **Phone Numbers > My Numbers**.
> 2. Select the desired **DID number** and click on the voice trunk field.
>
> Note
>
> If the DID has no trunks assigned, the trunk field will display `Voice: none`.
>
> 3. Assign the **Load Balancing Trunk Group** and click **Confirm**.
>
> [![Assigning the Trunk Group to a DID Number.](../../_images/fig6e4.png)](../../_images/fig6e4.png)
>
>
> **Fig. 12.** Assigning the Trunk Group to a DID Number

### Result

> - Calls with prefix `1` (US) are routed to **US SIP Trunk**.
> - Calls with prefix `44` (UK) are routed to **UK SIP Trunk**.
> - All other calls are rejected by default.

This setup allows a single DID number to intelligently route incoming traffic to country-specific trunks, improving
routing efficiency and regional control.

Tip

Scale the trunk group to include as many trunks and number lists as needed to achieve traffic load balancing in expected
countries or regions.

---

# Additional Resources

**Inbound Number List**

Learn how to create, configure, and manage Number Lists to filter inbound calls by allowing or rejecting specific
numbers or prefixes linked to SIP trunks.

[Inbound Number Lists](number-lists.html#user-panel-voice-in-numberlist)

**Create a SIP trunk**

Create and configure SIP trunks for inbound calls, set transport protocols, authentication, media options, and more.

[SIP Trunk](creating-a-new-sip-trunk.html#user-panel-sipin-trunk)

**Create a Trunk Group**

Discover how to create and configure a trunk group for failover and load balancing purposes.

[Trunk Groups](creating-a-new-trunk-group.html#user-panel-trunk-group)

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