# Blocklist

The Blocklist module helps you manage unwanted calls by automatically terminating calls from specific phone numbers or suspicious caller IDs.

:::tip[Common Uses]
- Block spam or nuisance callers
- Filter out automated calls
- Prevent calls with suspicious caller IDs
- Manage call access control
- Protect your phone system from abuse
:::

![Blocklist module](/docs/phone-system-guide/modules/img/blocklist-module.png)

## Setting It Up {#setting-it-up}

![Blocklist configuration interface](/docs/phone-system-guide/modules/img/blocklist-create.png)

Configure your blocklist with these settings:

1. **Name**: Give your blocklist a descriptive name (e.g., "Spam Filter" or "Security Blocklist")

2. **Additional Settings**:
   - **Block empty Caller IDs**: Automatically block calls with no caller ID
   - **Block Caller IDs containing letters**: Block calls where the caller ID includes alphabetical characters

3. **Blocked Numbers**: Add specific phone numbers to block
   - No format restrictions (E.164 not required)
   - No limit on number of digits
   - Add multiple numbers as needed
   - Remove numbers using the "X" icon

:::note
Blocked calls are terminated immediately and will not proceed to any modules connected after the Blocklist.
:::

## How It Works {#how-it-works}

The Blocklist evaluates incoming calls in this sequence:
1. Checks if caller ID is empty (if enabled)
2. Checks if caller ID contains letters (if enabled)
3. Compares against list of blocked numbers
4. If any check is positive → Call is terminated
5. If all checks pass → Call proceeds to next module

## Practical Example {#practical-example}

![Blocklist usage example](/docs/phone-system-guide/modules/img/blocklist-example.png)

This example shows a typical setup:
1. Incoming calls arrive through a [phone number](./phone-number.md) or via the iOS/Android [App configuration](./ring-group#app-configuration-settings).
2. Blocklist filters unwanted calls
3. Valid calls proceed to the [Voice Menu](./voice-menu.md)

:::tip[Best Practices]
- Regularly review and update blocked numbers
- Test blocklist settings before going live
- Document reasons for blocked numbers
- Consider using [Caller Router](./caller-router.md) for more complex filtering
- Keep backup of blocked number list
- Monitor blocked call patterns
:::

## Advanced Tips {#advanced-tips}

| Feature | Description | Best For |
|---------|-------------|----------|
| Empty CLI Blocking | Block calls with no caller ID | Preventing anonymous calls |
| Letter Detection | Block alphanumeric caller IDs | Filtering automated systems |
| Number Blocking | Block specific phone numbers | Known spam numbers |
| Flexible Format | Any number format accepted | International numbers |

:::note[Important Considerations]
- Blocked calls are terminated immediately
- No notification is sent to blocked callers
- Blocking is based on exact number matches
- Keep your blocklist up to date
- Consider legitimate uses of blocked features (e.g., some business systems use alphanumeric caller IDs)
:::