Document : Licensing Windows Server 2008 Terminal Services
Microsoft licensing policies for Windows Server Terminal Services, including the new components that are included in Windows Server 2008, require that in addition to a Windows Server Client Access License (CAL), Microsoft® Core CAL Suite, or Microsoft Enterprise CAL Suite, you must acquire a Windows Server 2008 TS CAL for each user or device that directly or indirectly accesses the server software to interact with a remote graphical user interface (using the Windows Server 2008 Terminal Services functionality or other technology).
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