# Enable or Disable Call Waiting for Cloud Voice App UC Clients

Call waiting lets an extension take a new incoming call while the user is already on an active one. As an administrator, you can turn the feature on or off for an extension's Cloud Voice App (the user's unified communications, or UC, clients), and your choice is pushed automatically to that user's mobile, desktop, and web apps.

## Requirements

Before you configure call waiting, confirm that the PBX (Private Branch Exchange, the phone system) and the user's apps meet these minimum versions.

| Server / Client | Version requirement |
|-----------------|---------------------|
| PBX server | 84.17.0.16 or later |
| Cloud Voice App (mobile) | iOS: 5.8.2 or later; Android: 5.8.3 or later |
| Cloud Voice App (desktop) | Windows: 1.8.3 or later; Mac: 1.8.3 or later |

:::caution
These are minimum versions. If a user's Cloud Voice App is older than the version listed, the call waiting setting may not sync or take effect. Update the app to a supported version before you configure the feature.
:::

## Set call waiting for an extension

1. Sign in to the PBX web portal and open **Extension and Trunk > Extension**.
2. Next to the extension you want to change, select the edit icon ![Edit an extension](/images/pbx/edit-1.png), then open the **Cloud Voice App** tab.
3. Turn **Call Waiting** on or off for the client you want to configure.

   
   ![Cloud Voice, the Call Waiting toggle on an extension's app settings](/images/pbx/call-waiting-for-an-extension.png)

4. Select **Save**.

## Result

The setting syncs to the user's Cloud Voice App and takes effect right away. How the system handles a second incoming call depends on the setting:

- **Call waiting off**: When a second call arrives during an active call, the system plays "The extension you dialed *{extension_number}* is busy now." and then drops the new call.
- **Call waiting on**: When a second call arrives during an active call, the system plays "Please hold on, the extension you dialed *{extension_number}* is busy now.", and the user hears a tone signaling the waiting call.

:::note
Extension users can also manage call waiting themselves from their Cloud Voice App. On the desktop and web app, they go to **Preferences > Features > Call** to adjust the setting; the mobile app offers the same option in its own settings.
:::