by | March 22, 2016

I’m certain you’re doing your best to keep your organization compliant with Microsoft licensing rules. But when it’s your turn to be audited, don’t be surprised if Microsoft uncovers unintentional mistakes that cost millions of dollars to fix. A good example of how this might happen is the often overlooked Microsoft licensing rules for something called multiplexing.

The Multiplexing Trap

You already know that most Microsoft server products require Client Access Licenses (CALs), which comprise a majority of total licensing costs for those products. In general, all employees or on-site contractors accessing instances of a server product that require user CALs need CALs for themselves or for the devices they use to access the server product.

What you may not realize is that a CAL is also required for users or devices that indirectly access server product instances through an intermediary, a scenario Microsoft refers to as multiplexing. This means that integrating two systems can obligate an organization to buy many more CALs than they might expect.

For example, an organization might synchronize cost and timesheet data between its enterprise resource planning (ERP) system and Microsoft’s Project Server, a project management server application. In that case, the organization needs Project Server CALs for all employees that use the ERP system, even if they never use Project Server directly.

Tread Carefully in the Cloud Too

Microsoft online services customers are not immune to the multiplexing trap.  For example, an organization that integrates their on-premises directories or databases with Microsoft-hosted services could end up needing many more User Subscription Licenses (USLs), which an organization’s employees need to access Microsoft-hosted cloud services like Office 365,  than they expect because on-premises users are indirectly accessing online services through the on-premises system.

What can you do?

The only sure way to avoid compliance mistakes like the multiplexing trap is to educate yourself. We’ve prepared an incredibly useful guide to help you understand Microsoft CALs and how they impact your Microsoft licensing costs and compliance position. You can request your complimentary copy here:

Or, if you want to quickly get up-to-speed on all the current Microsoft licensing rules, consider our fantastic two-day Microsoft Licensing Boot Camp. It’s the fastest way to get the knowledge and understanding you need to keep your organization compliant without overbuying.

For more information, please visit


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