Licensing Brief - Base and Additive Client Access Licenses: An Explanation

Applies to all Volume Licensing Programs


Server software that requires Client Access Licenses (CALs) offers one base CAL and may offer one or more additive CALs. Base CALs license access to server functionality. Additive CALs license access to advanced server functionality and must be licensed in addition to the corresponding base CAL. Both types of CALs are available for both users and devices.

What’s New in this Brief

  • This brief replaces a previous version published in April 2010.

  • Significant changes in this new version include:

    • Revised text and improved figures to illustrate CAL suite license options

    • Updated references to Lync Server (formerly Office Communications Server)

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