BLF keys (Busy Lamp Field) show the status of a user at a glance and can be convenient for knowing the status of a user before calling them, transferring calls to a user, conferencing in a user or picking up ringing calls.
Meaning:
Each phone can have up to 10 BLF keys, you can cycle between pages using the page-turn button.
You can connect to a user by pressing the corresponding key next to their name.
You can edit the BLF Keys from the admin portal.