Administrator’s Guide for Akuvox SP-R5xP IP Phones
Akuvox Proprietary and Confidential. Copyright © 2014 Akuvox network Co., Ltd..
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Busy Lamp Field
Busy Lamp Field (BLF) is a light on an IP phone which tells you whether another extension
connected to the same PBX is busy or not. When an IP phone is configured to monitor an
extension it sends a SUBSCRIBE SIP message to the PBX. If authentication is configured,
authentication takes place and if the subscriber is successfully authenticated a 200 OK SIP
message response is sent back to the subscriber. A NOTIFY SIP message which includes XML in
the message body is sent to the subscriber (in this case the phone) to advise the subscriber the
current state of the extension being monitored. Once status of monitored extension is changed
from idle to busy or vice versa, the subscriber is notified from the PBX with a NOTIFY SIP
message.
When the monitored user is idle, the supervisor presses the BLF key to dial out the phone
number. When the monitored user receives an incoming call, the supervisor presses the BLF
key to pick up the call directly. When the monitored user is in a call, the supervisor presses the
BLF key to interrupt and set up a conference call.
Note:
