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HPE OEM Microsoft Windows Server FAQ Series- Part 7: Client Access Licenses (CALs)


This month, our Coffee Coaching blogs focused mainly on Microsoft Windows Server Client Access Licenses (CALs). So far, we have given you an introduction to CALs in “Introduction to HPE OEM Microsoft Client Access Licenses (CALs)” and  have reviewed the different types of CALs in “What are the different types of Client Access Licenses (CALs) and which do your customers need?”.


Today, we want to help answer any other questions you may have about CALs as we discuss the 7 most frequently asked questions we hear about CALs.

1. What is a CAL?
A Client Access License (CAL) is a license that grants access to Microsoft Windows Server software. CALs are used in conjunction with Microsoft Windows Server Operating System (OS) licenses to allow users and devices to access and utilize the services of that server software. Windows Server OS licenses only allow the OS to run on the physical server it is licensed for. To provide the rights for users or devices to access the Windows Server OS software running on the server, Windows Server CALs are required.

2. What are the different types of CALs?

Device CALs: Acquire an access license for every device (used by any user). Device CALs make the most economical and administrative sense for an organization that has multiple users for one device, such as shift workers.
For example one computer used by 2 people, needs one Device CAL.  

User CALs : Acquire an access license for every named user accessing your servers (from any device). User CALs make the most economical and administrative sense for an organization with many roaming employees who need access to the corporate network from unknown devices.
For example, one user accessing the company network through their laptop and their cellphone, required one User CAL.

RDS CALs: Remote Desktop Service (RDS) CALs are required along with Device CALs or User CALs for any device or user that needs to access programs, or the full desktop, remotely.
For example, an IT network administrator who needs to reboot the server remotely.

3. What is the difference between a Windows Server CAL and an RDS CAL?

A Windows Server CAL is required when a user or device is directly or indirectly accessing Windows Server. A Remote Desktop Service (RDS) CAL is also required for users that need to access programs or the full desktop remotely. Both a Windows Server CAL (user or device) and a RDS CAL (user or device) are required for remote desktop access. RDS CALs contain a product key for activation. As an exception to these rules, up to two users or devices may access the server software, only for server administration purposes, without requiring either a RDS CAL or a Windows Server CAL.

4. Are CALs still required for Microsoft Windows Server 2016?
Windows Server Standard and Datacenter Editions will continue to require Windows Server CALs for every user or device accessing a server. Some additional or advanced functionality will continue to require the purchase of a RDS CAL. RDS CALs are needed in addition to the Windows Server CAL to access functionality, such as Remote Desktop Services.

5. Is it possible to purchase additional CALs after the Windows Server license purchase?
Yes, customers can buy additional CALs from HPE or HPE authorized resellers at any time and do not require a new HPE server purchase. HPE currently offers one, five, ten, and fifty CAL packs (user or device) and five CAL packs for RDS CALs (user or device).

6. Can Windows Server 2012 R2 CALs be used to access Microsoft Windows Server 2016?
No. CALs must be the same version as—or higher than—the server software they are accessing. In other words, users or devices accessing a server running Windows Server 2016 must have Windows Server 2016 CALs.

7. Can Windows Server 2016 CALs be used to access Microsoft Windows Server 2012?
Yes. A Windows Server CAL permits access to all earlier versions of Windows Server.

Have questions about HPE OEM Microsoft licensing,  CALs, or Windows Server 2016? Join the Coffee Coaching community to keep up with the latest HPE OEM Microsoft news and interact with HPE and Microsoft experts.  Follow us on Twitter - Join our LinkedIn group - Like us on Facebook - Watch us on YouTube

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About the Author


Willa manages the HPE | Microsoft Coffee Coaching program. Follow along to learn more about the latest HPE OEM Microsoft product releases and how the HPE Microsoft partnership can benefit partners and customers.

Samuel Trejo

Hi, i have one Question, its possible to use RDS Cals 2016 on a windows server 2012?



Hi Samuel, 

Yes. A Windows Server 2016 RDS CAL can be used on Windows Server 2012. To do this, the RDS CAL will need to be downgraded to Windows Server 2012.  You can do this by following the steps outlined in the FAQ below. 

What do you need to do if you want to downgrade your RDS CALs or a TS CAL?
To downgrade TS/RDS CAL, call the TS Clearinghouse and obtain Windows Server TS CAL key (refer to TS downgrade rights):
- In the U.S., call (888) 571-2048.
- Outside the U.S., click Start, point to Programs, click Administrative Tools, and then click Terminal Services Licensing.
- In the Terminal Services Licensing console, right-click your license server, and then click Properties.
- Click Connection Method, and then click Telephone.
- Click the appropriate country, and then click OK.
- On the Action menu, click Install Licenses, and then click Next.
- Call the appropriate customer service Center using the telephone number that is displayed.
- Click Cancel to exit the Terminal Services Licensing console

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