When you configure Presence in Cisco Unified Communications Manager Administration, an interested party, known as a watcher, can monitor the real-time status of a directory number or SIP URI, a presence entity, from the device of the watcher.
Cisco Unified Communications Manager controls which destinations a watcher can monitor with presence groups. A presence group contains watchers and the destinations that can be monitored by the watchers in the group. To allow watchers in one group to monitor directory numbers in other groups, you specify permission settings to allow or block (disallow) the presence request. Presence authorization works with the presence groups that are configured to ensure that a watcher has permission to monitor the status of a destination.
After you configure the presence groups, you apply a presence group to the following items in Cisco Unified Communications Manager Administration:
•Directory number—Presence entity for which you want status
•Phone that is running SIP—Watcher
•Phone that is running SCCP—Watcher
For information about configuring presence groups, refer to the "Presence" chapter in the Cisco Unified Communications Manager Features and Services Guide.