I'm trying to get BLF (Busy Lamp Field) working in 3CX. I can add BLF monitors to the "Soft Keys" area, but they always show in gray instead of indicating the status of the monitored extension. We are using a GrandStream UCM6108 PBX. Their instructions for BLF say that you need to make an Event List in the PBX, and then enter the URI of the event list into the phone for it to subscribe. But I don't see anywhere to enter an Event List URI in 3CX Phone. Is this why BLF is not working? Or is there a different way to get it to work? The extensions I wish to monitor are also using 3CX Phone.