# Block Calls To or From a Phone Number

Nuisance calls and unwanted destinations can be shut out at the system level. Cloud Voice lets you build a blocklist of phone numbers and choose whether each entry stops calls coming in, calls going out, or both directions at once.

## What you can and can't block

The system blocklist applies to external phone numbers only. Keep the following limits in mind:

- Internal extensions are never affected. If a number on the blocklist happens to match an extension inside the PBX (your Private Branch Exchange, the phone system itself), that extension keeps working normally for both inbound and outbound calls.
- The number of blocklists you can create, and how many entries each list holds, scale with your extension count:

| Number of extensions (N) | Blocklists allowed | Entries per blocklist |
| --- | --- | --- |
| N ≤ 200 | 256 | 100 |
| N > 200 | 512 | 200 |

:::caution
These are hard limits. Once a list is full, or you have created the maximum number of lists for your extension count, the system will not let you add more until you remove existing entries. Plan a list per purpose (for example, one for known spam, one for restricted destinations) rather than one giant list.
:::

## Two ways to filter calls by number

Cloud Voice offers two approaches to handling calls based on the phone number involved. Pick the one that fits your goal:

- **Caller ID call handling**: Build per-extension rules that route or block incoming calls from specific internal or external numbers. Because the rules live on each extension, different users can treat the same caller differently. See [Handle Incoming Calls Based on Caller ID](/pbx/administrator-guide/handle-incoming-calls-based-on-caller-id/).
- **Blocked numbers**: Add a number to the system-wide blocklist and no extension on the PBX can call it or be reached by it. This is the feature described below.

:::note
The system blocklist takes precedence over any blocklist configured on an individual extension. If the two disagree, the system-wide entry wins.
:::

## Create a blocklist

1. Sign in to the management portal and go to **Call Features > Blocked/Allowed Numbers > Blocked Numbers**.
2. Click **Add** to start a new blocked number list.
3. Fill in the dialog that opens:

   ![Dialog for naming a blocklist and entering the numbers and direction to block](/images/pbx/add-blocked-numbers.png)

   - **Name**: A label that helps you recognize what this list blocks. Choose something descriptive, such as `Spam - robocalls` or `Restricted - premium dialing`, so a teammate can tell at a glance why the list exists.
   - **Number**: Enter one number or number pattern per line:
     - For a single number, type it exactly, for example `2126420000`.
     - For a range, use a wildcard pattern. For example, `9011.` blocks every number that begins with 9011. For the full set of wildcard characters, see [DID Pattern and Caller ID Pattern](/pbx/administrator-guide/did-pattern-and-caller-id-pattern/) (DID stands for Direct Inward Dialing, the direct-dial format your numbers use).
   - **Type**: Choose the direction to block from the drop-down:
     - **Inbound**: The number(s) cannot call into the PBX.
     - **Outbound**: Extensions cannot dial the number(s).
     - **Both**: Blocks calls in both directions.

   :::tip
   Add one number or pattern per line, and keep wildcard patterns as narrow as you can. A pattern like `9011.` is precise; a broad pattern such as `9.` would sweep up far more numbers than you intend. Test any pattern against a sample number before you rely on it.
   :::

   :::danger
   An **Outbound** or **Both** block is system-wide: every extension in the account immediately loses the ability to dial the matching number(s). Before saving an outbound rule, confirm the number or wildcard pattern can never match an emergency number such as 911. Blocking outbound calls to emergency services would stop staff from reaching help during a crisis and put lives and E911 (enhanced emergency calling) compliance at risk.
   :::
4. Click **Save**, then **Apply**.

:::caution
Changes are not live until you click **Apply**. Saving alone stages the list; **Apply** commits it to the running system, at which point the block takes effect for all extensions.
:::

## Result

Your new list appears on the Blocked Numbers page, and each entry is enforced according to the direction you selected.

![Blocked Numbers page listing a saved blocklist entry](/images/pbx/add-blocked-numbers-successfully.png)