The global-level presence settings that control the maximum number of devices apply to all Session Initiation Protocol (SIP) users in an Active Directory forest. Reasonable limits based on your infrastructure help ensure optimum throughput and performance.
To specify the maximum number of devices per user
Open the Office Communications Server 2007 R2 snap-in.
In the console tree, right-click the forest node, click Properties, and then click Global Properties.
On the Usertab, in Maximum devices per user, type a number from 1 through 64 for the maximum number of endpoints that a registered user can have. The default is 8.