The busy light will automatically illuminate when the microphone is activated. You may also manually turn the busy light on and off. Pressing the button once will cause the LED to manually illuminate as a solid red LED light. Pressing and holding it for 2 seconds will cause the red LED light to pulse/blink. Pressing it again in either status (solid or pulse) will cause the LED to be manually turned off. The busy light is seen on your in-line controls and on the back of the microphone so colleagues can see that you are busy.