CAL (Client Access Licence) are necessary in many cases in order to have a fully legal licensing. The best known and most commonly used are Windows server, RDS, SQL server and Exchange Server CALs.

Why are CALs (Client Access Licences) needed?

CALs are used to grant access rights, either to users and/or devices, to the server in question. This means that when we buy a licence (Windows Server, SQL server or Exchange Server) we have the right to install one of these systems on the server, but it does not give us the legal right for others to connect to that machine. This is why CALs are needed.

One thing to keep in mind is the version of the CAL licences, as they allow us to access systems of the same or earlier versions, not later ones. For example: Buying Windows server User CAL 2019 licenses we can access a server licensed with Windows server 2019, Windows server 2016 and Windows server 2012, but we will not be able to access if the server is licensed with Windows Server 2022.

Depending on the needs and infrastructure of our company, one type of CAL or another will suit us.

Types of CAL Licences

We have the possibility of choosing between two types: User CAL (per user) and Device CAL (per device), although we can have a combination of both depending on our needs:


User CALs are linked to each user that will access the server; using services such as printing files, storage… regardless of the different devices they use.

This is the best option for companies with users who need to access the corporate network with different devices, or when these devices are unknown. We will save costs with this type of CAL if the number of devices exceeds the number of users.


This type of CAL is tied to the device. Instead of licensing users, we license per machine regardless of the number of users using it.

This would be the recommended licensing option in companies where there are more users than devices; for example, if workers use the same device on different shifts, as might be the case in a contact centre company.

When do you need to buy CAL?

Windows Server and CALs

To legally access a server licensed with Windows Server, with Standard or Datacenter editions, you will need CALs, either user or device.

In addition to these two types, we also have RDS, which are remote desktop access licences. In this case, we also have the possibility of acquiring RDS User CAL or RDS Device CAL licences.

Read more about licensing servers with Windows Server.

SQL Server and CALs

In the case of SQL server, we have the option of licensing through the “Server + CAL” option or through “Licenses per core”, depending on our company size and infrastructure it will be more convenient, and economical, to license in one way or the other.

SQL Server + CAL

If the company is relatively small or has a reduced infrastructure, this model is usually more economical. In this case we find the SQL Standard version, also available for the per-core licensing option.

SQL Sever per core

In this case there are two options: SQL Server Standard, also available via “SQL Server + CAL”, and SQL Enterprise which is only available for per-core licensing. With this option we do not need to purchase any CALs.

This tends to be the most cost-effective model for large corporations or companies with considerable infrastructure.

Read more about SQL Server.

Exchange Server and CALs

For Exchange Server we will need to purchase, as with Windows Server, CAL licences to complement our licensing, both for the Standard and Enterprise versions.

At CHEAPFY, you can buy CAL licenses, both User CAL, Device CAL and RDS, for Windows Server, SQL Server and Exchange Server at the best price. Our pre-owned CAL licenses are completely legal, one-time payment and perpetual.

If you have any questions about CAL licenses or used, second-hand licenses, please contact us!

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