Client Access License (CAL)

If your company's workstations are networked, you will utilize a network server and the workstations on the network will access that server(s) software to perform certain functions such as file and print sharing. In order to legally access this server software, a client access license or CAL may be required. A CAL is not a software product; rather it is a license that gives a user the right to access the services of the server.

Due to the technical nature of server products, CAL licensing can be a complicated area. We have created the following information to help you determine the need for CALs. This guide is for reference purposes only and should not be used for purchasing decisions. Before purchasing you should visit the "How to Buy" section for each product and consult your local reseller.

The table below provides information on a variety of Microsoft Server products and the licensing of CALs as it relates to those products. Before you read about how CALs apply to each product, referring to the sections of this guide on "Per Seat", "Per Server", "Per Processor", and "Per User" licensing will be helpful.

	Per Seat Licensing
	Per Server Licensing
	Per Processor Licensing
	Per Mailbox Licensing Per Seat Licensing With Per Seat licensing (sometimes referred to as "Per Device or Per User"), you need a separate CAL for each unique device (or user, if applicable) that accesses the server to avail of services such as file or print or to run Microsoft server applications. Once you choose to deploy a Microsoft server product in Per Seat mode, your choice is permanent. The following is a diagram illustrating Per Seat licensing: Diagram 1 - Per Seat Licensing Per Seat licensing is available for the following Microsoft products in the server software pool: Class Server Exchange Server Office Project Server Office SharePoint Portal Server Office Live Communications Server SQL Server Systems Management Server Terminal Server Windows Rights Management Server Windows Server Windows Small Business Server Per Server Licensing With Per Server licensing, a specified number of CALs are associated with a particular server. The number of devices that can legally access that server simultaneously is limited in Per Server licensing to the number of CALs purchased for that particular server. For example, if your organization chooses to deploy Microsoft Windows Server 2003 in Per Server mode, purchasing 50 CALs will allow up to 50 unique devices to be connected to that server simultaneously. Because CALs in Per Server deployments are not permanently associated with a specific device, if your organization adds another Windows Server, and remains deployed in Per Server mode, separate Windows Server CALs will be required to access the second server. With Per Server deployments, the system administrator designates the number of CALs that apply to the server during setup, based on the number that has been purchased for that server. The following is a diagram illustrating Per Server licensing: Diagram 2 - Per Server Licensing Per Server licensing is available for Windows Server. Per Processor Licensing Some of the server products are available Per Processor. Under the Per Processor model, you acquire a Processor License for each processor in the server on which the software is running. A Processor License includes access for an unlimited number of users to connect from either inside the local area network (LAN) or wide area network (WAN) or outside the firewall. You do not need to purchase additional server licenses, CALs, or Internet Connector Licenses. Per Mailbox Licensing If you are an education customer using Exchange Server, you have the additional option of deploying licenses in Per Mailbox mode. With this model, you acquire one CAL for each unique mailbox accessing Exchange Server. If you choose the Per Mailbox mode, you may not later change to Per Seat mode. However, if you initially choose the Per Seat mode, you may transition one time only to Per Mailbox mode. This choice is then permanent.