Microsoft is gradually improving the way it allows for Bring Your Own Device (BYOD) and other scenarios in which many employees use Microsoft on multiple devices. We’re getting growing numbers of questions from Forrester clients about this topic, and while Microsoft is making its approach fairer in some areas, it's also making it more complicated. One problem is that different Microsoft product teams continue to invent new ways to handle BYOD that are OK for their product but are inconsistent with how other product teams handle the same situation. Sourcing professionals need to understand all the different rules, so that they can work with IT colleagues to create a BYOD strategy that balances technical requirements and licensing cost, to take advantage of the available flexibility while avoiding the potential pitfalls. For example, Microsoft has announced cheaper, better BYOD support for the Windows client OS, but you might face significant extra costs for Microsoft Office if you enable it for BYOD unless you take care to avoid them.

Of course the fundamental problem is that per-device licensing is an obsolete model, so Microsoft should really enable BYOD by allowing per-user licensing, at least for Enterprise Agreements. However, since that isn’t going to happen anytime soon, sourcing professionals need to be able to navigate the per-device rules. Here’s as simple an overview as I can create:
•    By default, ownership is irrelevant, so a device is a device. A device is something that a human being uses to access the Microsoft software, with input (keyboard/mouse/touchscreen) and output (internal display &/or external monitor). Were it not for Microsoft’s special policies such as roaming use rights you would need to buy licenses for every device that your employees use for work purposes, wherever they are (at work, at home, in the hotel business center) and whoever owns the device (your company, the employee, the hotel). It doesn’t matter where the software is installed or running, so whether the hard disk, RAM, and CPU are in the device or in your data center, you still need licenses for the thing with the screen and the keyboard.
•    Microsoft does have per-user licensing options for some products. For instance, you can buy user CALs instead of device CALs for Windows server, Exchange, and SharePoint. You can even mix the two types, buying user CALs for people who have iPads and Blackberrys in addition to their work PC, and device CALs for kiosk PCs that several people use.
•    But not for the Windows client OS. Microsoft gets between $50 and $100 for every PC sold, and since companies replace hardware more frequently than they upgrade OS, it could lose a lot of revenue moving to per user. Moreover, Microsoft sees people running Windows desktops on additional devices as additional customer value, for which they should charge, rather than shifting value from one device to another with no net gain, as users might perceive it. Therefore, unless they have special rights as part of their software assurance (SA), customers have to buy Windows licenses for their additional PCs, or the Virtual Desktop Access (VDA) license for remote access from non-Windows devices, such as tablets or thin clients.
•    With Windows 8, ownership becomes relevant. The policy isn’t finalized, but parts of it have been pre-announced here ==> (Introducing Windows 8 Enterprise and Enhanced Software Assurance for Today’s Modern Workforce). Now you’ll get 3 options for additional devices used by employees that have a primary device assigned to them that you’ve covered with SA. The rights, which apply to VDI for any Windows version, and also to Windows-to-go (WTG) — a version of Windows 8 that runs from a bootable USB stick — are:
1.    Free roaming use rights, from devices that are never brought on company premises.
2.    Free VDA, for company-owned Windows RT devices used anywhere.
3.    A companion device license add-on SKU, for BYOD use. The official TLA is TBD, but we’ll call it CDL for now.
•    The new options don't apply to Microsoft Office. You can license Office per user as part of Office365, or via the separate Office Subscription product, but perpetual licenses are per-device. You get roaming use rights with SA, but those don’t cover true BYOD (i.e., where the employee brings his own device on-site).
Bottom Line: Enterprises considering how to support employees’ multi-device access requirements need to understand Microsoft’s licensing rules so they can align their Microsoft negotiation and BYOD strategies.
The best way to gain that understanding is to come along to Forrester’s workshop on  Jul 24/25: Successfully Negotiating Your Microsoft Licensing Agreement in Cambridge, MA. It’s a two-day event, packed with great material, entertaining exercises, and valuable peer interaction. I hope to see you there.