Asterisk Feature Busy Lamp Field (BLF)
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Introduction
The busy lamb feature allows users to monitor the dialog state of another phone/user extension. This is indicated by the LEDs adjacent to an FPK. This feature is called "Busy Lamp Field" in the Asterisk community. Sometime the term 'Direct Station Selection' is used for the same functionality.
For Users
The basic Busy Lamp field feature allows the user to monitor the dialog state of another phone/user extension. The dialog state is shown by a distinct LED behavior:
- LED off -> Watched extension is idle
- LED blinking -> Watched extension is ringing
- LED on -> Watched extension is busy/connected
In the basic configuration pressing the FPK will call the monitored persion in any call state
Example:
There are four users: Leo, Alice, Joe and Bob. Leo is watching the extensions of Alice, Bob and Joe. Each of the extensions are configured on an specific FPK. The example shows the three different extension status. Joe is talking to annother persion, Alice gets a call, her phone is ringing and Bob is in idle like Leo is. The following picture shows this example:
For Administrators
The FPK are administrated as Server Key. This is one option of the FPK programming options. The configuration can be found in
Administrator Pages -> System -> Features -> Program Keys:
The FPK function is ‘Server Feature’. Select this option and press ‘Edit’
Within the server feature four options are given:
Key label - This is the label of the selected FPK
Feature Code - This code is sent within an INVITE message, if the key is pressed in idle status
DTMF Digits - These Digits are sent as DTMF signals, if the key is pressed during a call
LED control - A Subscribtion is sent to the given URL
Example:
If Bob has the extension numer 222, the parameters will be:
Key label - Bob
Feature Code - 222, pressing the FPK will always call Bob independant of his line status..
DTMF Digits - n.a.., not neccessary in this feature
LED control - 222@192.168.6.10, a subscription for the LED will be sent to the server at the IP address 192.168.6.10. If no IP address is given, the request will be automatically sent to the configured SIP proxy server.
Technical Backround
The BLF features give the user the possiblity to watch one other users dialog state
