Busy lamp field
The busy lamp field (BLF) ( English busy lamp field ) is a function of system phones indicate to the busy information of the connected subscribers on other phones.
The fields are either integrated in the phone or connected to the phone as an additional module and usually consist of several speed dial buttons with an associated LED. If one of the subscribers stored on the speed dial buttons is called, the corresponding LED flashes - if his line is busy, it lights up continuously.
The buttons have different functions depending on the status of the subscriber: If the subscriber is free, he is called when the corresponding speed dial button is pressed, if the subscriber is currently being called, the call can be picked up by pressing the button.
VoIP telephones now also offer this function, provided the VoIP server supports it.