Application Note

Additional features
283
Busy lamp field
The Busy Lamp Field (BLF) is an alternate presence-monitoring
mechanism for the IP Deskphone that allows presence functionality on
proxies that support BLF.
BLF is an icon state for a corresponding Speed Dial key on an IP phone;
the icon state tells you if another extension connected to the same SIP
server is busy. You do not enable or disable this feature; BLF is
configured by your system administrator. If enabled, the IP Phone
subscribes to the proxy and receives the presence state list for all the
users it is configured to watch. Call states and the corresponding
presence icons are shown in the following table:
Note: If you have the required permissions you can answer a call
placed to a monitored IP Phone. To answer, press the flashing
Ringing button.
Table 18: Call states and corresponding Presence icons
State Meaning Icon
Unknown The presence of the monitored IP Phone
is unknown
Terminated The monitored IP Phone is not involved
in a call and is available
Ringing The monitored IP Phone is ringing
Flashing
On the phone The monitored IP Phone is busy on a call