About Client Access Licenses in Windows Essential Business Server

Microsoft Software License Terms for Windows EBS give you the right to install and use the server software. However, every connection to the Windows EBS network requires a Windows EBS client access license (CAL) to provide a network user with access to network resources. In Windows EBS, a single CAL provides access to the product services and resources that are enabled by the integrated server solution.

Use the Install CAL Packs Wizard to install CAL packs that you purchase for Windows EBS. The wizard guides you to install and activate your CALs. After the CALs are activated, they are stored in a secure license store and validated for integrity.

You can monitor and manage your CALs for Windows EBS in the Administration Console. You are notified through the Administration Console if you exceed license limits so that you can maintain compliance with your license agreements.

CAL assignments

CALs for Windows EBS must be assigned to user accounts or networked devices for your users to log on to the Windows EBS network. If you assign a CAL to a user account, the user can log on to Windows EBS from any networked device. This might be practical for a user in your organization who needs roaming access and uses multiple devices.

If you assign a CAL to a networked device, any user in your domain (but only one user at a time) can log on to the network from the device. This might be practical if you have multiple users in your organization (for example, shift workers) who share a single computer or device.


When an unlicensed user attempts to log on to the network from an unlicensed device, the following error message may appear: “Your account is configured to prevent you from using this computer. Please use another computer.” To enable the user to log on, assign a CAL to the user account or the computer.

Windows EBS automatically licenses the following objects by default, and they do not require a CAL:

  • Domain administrator account   Windows EBS assigns a preinstalled CAL to the built-in Administrator account on the Management Server. If the Administrator account is disabled or you use a different account for domain administration, you must assign a CAL to the account that you use for domain administration. You must use a licensed domain-administrator account to add computers to the domain.
  • Servers   Windows EBS assigns a built-in license to each server in the domain, including the Management Server, Security Server, and Messaging Server. Any user in the domain can log on to the network from a server.

If you do not have a CAL available to assign to a user account or device, Windows EBS allows you to assign a temporary CAL until you bring your CALs into compliance. You can also reassign your CALs for Windows EBS when users leave your organization or computers are retired.

Additional references