Busy Lamp Field (BLF) is a light (green or red) indicator on your phone (or expansion module) which can be configured to indicate the status of certain conditions/features of ComPBX.

Examples of BLF which can indicate status are:

• Whether an extension is in use (whether a user is on the phone or not)
• Speed-dial when key is pressed
• Whether or not there is a call parked (awaiting retrieval by someone)
• Whether Call Flow Control has been enabled/disabled (useful for turning on/off open/closed IVR - with a simple button press)

A good example of the 'extension in use' BLF would be if someone calls in and wishes to reach Jim at extension 220. The receptionist would take a look at the BLF panel on their phone and see that Jim is on his phone (the light next to Jim's name is RED), the receptionist can then ask the caller whether or not they would like to leave a message, or try back later. If the caller wants to leave a message, the receptionist simply transfers the call directly to Jim's voicemail (*220).