Aastra Telecom 57I C53I User Guide

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Operational Features
41-001160-00, Rev 01  Release 2.0
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Operational IP Phone Features
Operational IP Phone Features
Busy Lamp Field (BLF)
The BLF feature on the IP phones allows a specific extension to be monitored for 
state changes. BLF monitors the status (busy or idle) of extensions on the IP 
phone.
Example
A Supervisor configures BLFs on his phone for monitoring the status of a 
worker’s phone use (busy or idle).  When the worker picks up his phone to make a 
call, a busy indicator on the Supervisor’s phone shows that the worker’s phone is 
in use and busy.
BLF Setting (For use with Asterisk)
On the 55i, 57i, and 57i CT, the busy and idle indicators show on the IP phone 
screen display next to the softkey or programmable key configured for BLF 
functionality.  When the monitored user is idle, an icon with the handset on-hook 
shows next to the BLF softkey or programmable key. When the monitored user is 
on an active call, a small telephone icon is shown with the handset off-hook.
On the 53i, the LED lights next to each BLF programmable key illuminate steady 
to indicate the monitored line is off-hook or unregistered. The LED goes off when 
the line is idle.
Note: 
The BLF setting is applicable to the Asterisk server only.