A BLF (Busy Lamp Field) can be used to monitor the status of another extension, the agent login/logout status or agent pause/unpause status within a queue.
To monitor another extension, simply input the SIP username for the extension you wish to monitor as a BLF key on your phone. An example from Grandstream to monitor extension 102 is below.
BLF Monitoring of Queue Login/Logout or Queue Pause/Unpause
Step 1: Go to Configuration > Flows & Variables. You will need to setup a Flow for each agent extension in the queue. Set the destination(s) to "Toggle Login/Logout caller to [Queue Name]". Note, if you have multiple queues you will want to add each queue as a destination on your Feature Code so that the Flow will log the user in or out of all desired queues.
Next, choose the Monitor Type, monitored queue and extension to monitor. Note that you cannot choose multiple queues in the Monitoring section. Simply choose any of the queues referenced in the destination(s) above for monitoring. Since the destination(s) will log the caller in/out of all queues, we only need to monitor the login/logout status of a single representative queue.
Define a Flow per the above instructions for each queue agent extension you wish to monitor.
Step 2: Setup the BLF on your phone as follows on each agent phone using the applicable Flow defined above.
You will now have a BLF button on your phone that when pressed will login/logout of all queues defined in the Flow. The BLF will illuminate RED when logged out and GREEN when logged in.
The above procedure can also be used to create BLF to monitor whether an agent extension is paused or unpaused.