Microsoft has established itself as a leader in the unified communications market, but their focus on the software side of things means that they don’t have an end-to-end solution. The up side for customers is that Microsoft does not lock you into using specific or proprietary hardware. That is what allows Microsoft to run marketing campaigns like “VoIP As You Are”.
The down side is that Microsoft does not provide the desk phones and other related hardware so they have to make sure they are forging alliances with companies that do to ensure that there are quality hardware products that are designed for and certified compatible with Microsoft Office Communications Server and the Microsoft Unified Communications platform.
According to this article from InformationWeek, Microsoft and HP announced a partnership to merge their resources in an effort to build an end-to-end unified communications solution and continue to battle Cisco and IBM for UC market share.