The Busy Lamp Fields are generally the little LED lights on telephones that are associated with extensions.

How It Works

Every phone has different options for their BLF lights. Typically, a green BLF is associated with a free or available extension, a red BLF light is associated with a busy or otherwise unavailable extension, and a blinking red BLF light is associated with an extension that is ringing.

Practical Uses

• Allow receptionists to immediately know if an extension is available to take a call without having to call the extension and possibly interrupt the destination with another call.
• Often used by the staff to simply look at the phone to see if their colleague is available to speak.