Windows Server is a server operating system that enables a computer to handle network roles such as print server, domain controller, web server, and file server and to be the platform for separately acquired server applications such as Exchange Server or SQL Server.

The purpose of this guide is to help you find the Microsoft System Center servers and licenses appropriate for your organization's needs.



Microsoft offers Windows Server through Stifter-helfen in the Standard and Datacenter editions. The two editions have identical features, but they differ in the number of virtual instances of the server software you are allowed to run.

  1. The Standard edition is designed for small-to-medium-sized organizations that need no more than two instances of the server software in a virtual operating system.
  2. The Datacenter edition is optimized for large-scale virtualization; its license allows one server to run an unlimited number of Windows Server instances.



For general licensing information, see the Windows Server 2012 Licensing & Pricing FAQ. (Pricing information does not apply to Microsoft products available through Stifter-helfen).

Detailed licensing information can be found by clicking the Download the current PUR document link on the left side of the Microsoft Product Use Rights page. Select the English language link from the list.

Server Operating System Licenses

The Standard and Datacenter editions of Windows Server both use processor-based licensing, with each license allowing up to two physical processors. A license can be applied to only a single server.

Standard Edition

For each Standard Edition software license you assign, you may run one instance of the server software at any one time in the physical operating system environment (OSE). You may also run two instances in virtual OSEs on the licensed server.

However, if you run two instances in virtual OSEs, the instance in the physical OSE may be used only to run hardware virtualization software and to manage and service OSEs on the licensed server.

Datacenter Edition

Datacenter Edition licenses include unlimited virtualization rights. You have the use rights to run an unlimited number of virtualized instances of Windows Server on the licensed server.

Client Access Licenses (CALs) and External Connector Licenses (ECLs)

A Windows Server user or device CAL is required for each user or device accessing or using the server software. The exception is anonymous Internet users, such as unidentified users browsing the organization's public website.

Alternatively, an organization can use a Windows Server ECL for a large number of authenticated external Internet users. An external user is a person who is not an employee or someone to whom you provide hosted services using the server software.

Remote Desktop Services

If the server is running Remote Desktop Services, separate Remote Desktop Services CALs or ECLs are required to access the services. Remote Desktop Services allows the remote execution of applications from a wide range of devices over virtually any type of network connection. It was known as Terminal Services before the release of Windows Server 2008 R2.

Rights Management Services

If the server is running Rights Management Services (RMS), separate RMS CALs or ECLs are required to access the services. RMS is information-protection technology that works with RMS-enabled applications to help safeguard digital information from unauthorized use. RMS functionality is included in the Windows Server license.

How to Get CALs and ECLs

Microsoft offers the CALs and ECLs for Windows Server and for Remote Desktop Services through Stifter-helfen. RMS licensing is not available through Stifter-helfen at this time.

Server Application Licenses

Licenses for server applications — such as SQL Server or Exchange Server — that run on the Windows Server platform are separate. General licensing requirements for server applications offered through Stifter-helfen can be found in the product descriptions. For details, see the Microsoft Product Use Rights document.


If you have earlier versions of Windows Server with active Software Assurance, you can upgrade to Windows Server 2012. See the Windows Server 2012 Licensing & Pricing FAQ for details.

For help upgrading, see the section "Upgrading previous retail versions of Windows Server to Windows Server 2012" in the Windows Server TechNet Library.

CALs, ECLs, and management licenses (MLs) work if they are for a version equal to or earlier than their server software. However, if you upgrade to Windows Server 2012, you will also need to use Software Assurance to upgrade the CALs.

CALs, ECLs, and MLs offered through Stifter-helfen are always for the currently offered version. The Windows Server and Remote Desktop Services licenses, including those in the Core CAL suites, apply to Windows Server 2012 and earlier versions. Windows Remote Desktop Services and Windows Terminal Services CALs are interchangeable.

Windows Server Products Available Through Stifter-helfen

The following servers and licenses are in the Windows Server family

  1. Windows Server 2012 Datacenter Edition
  2. Windows Server 2012 Standard Edition
  3. Windows Server licenses: External Connector, Device CAL, User CAL, Remote Desktop Device CAL, Remote Desktop User CAL
  4. Core CAL suites: Device, User

Stifter-helfen also offers other Microsoft products that can be used with Windows Server.