/mcpC H A P T E R 41 BLF Presence • BLF Presence Overview, on page 529 • BLF Presence Prerequisites, on page 529 • BLF Presence Configuration Task Flow, on page 530 • BLF Presence Interactions, on page 541 • BLF Presence Restrictions, on page 541 BLF Presence Overview 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 Call lists 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. To view the status of a BLF presence entity, watchers send BLF presence requests to Cisco Unified 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. Extension mobility users can use BLF presence features on phones with extension mobility support. BLF 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 Dials. BLF Presence Prerequisites • Configure the phones that you want to use with the BLF presence feature. Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs 529