The Busy Lamp Field (BLF) presence feature allows a user who is a watcher to monitor the real-time
status of another user at a directory number or Session Initiation Protocol
(SIP) uniform resource identifier (URI) from the device of the watcher.
A watcher can
monitor the status of the user or BLF presence entity (also called presentity)
by using the following options:
- BLF and SpeedDial buttons
- Missed call, placed call,
or received call lists in the directories window
- Shared directories, such as
the corporate directory
and directories display the BLF status for existing entries. When you configure
BLF and SpeedDial buttons, the BLF presence entity appears as a speed dial on the
device of the watcher.
the status of a BLF presence entity, watchers send BLF presence requests to
Communications Manager. After administrators configure BLF presence
features, real-time status icons appear on the watcher device to indicate
whether the BLF presence entity is on the phone, is not on the phone, the status
is unknown, and so on.
mobility users can use BLF presence features on phones with extension mobility
presence group authorization ensures that only authorized watchers can access
the BLF presence status for a destination. Because the administrator ensures
that the watcher is authorized to monitor the destination when a BLF or Speed Dial
is configured, BLF presence group authorization does not apply to BLF or Speed