The BlackBerry utilises an LED light to inform you of events, several of which could result in a flashing blue LED. A blue light often indicates a Bluetooth pairing, but it could also be the result of a different application such as the Blackberry Music Gateway or a third-party application.
When a BlackBerry pairs with a Bluetooth device, the LED light will flash blue to indicate that the connection has occurred. Often, when you initially pair the BlackBerry and Bluetooth device, the LED will glow blue for a period before commencing a flashing pattern. During the call, the LED will flash blue to reassure you of the connection.
Blackberry Music Gateway
The BlackBerry Music Gateway uses a blue LED to communicate with you. If you've paired the BlackBerry Music Gateway with your BlackBerry, the LED light will flash for a period of three seconds to inform you that the connection was successful. You may also notice a flashing blue light that is intermittent with red a light, which indicates that the device is ready to be paired.
Some third-party applications are capable of changing how your BlackBerry uses the LED light, so that a blue flashing light may indicate a variety of things within the application. To stop or change the flashing blue light, alter the settings within the application or remove the application.
If you like, disable this flashing blue LED notification by navigating to "Manage Connections" and then "Options." Change the settings under "LED Connection Indicator" to alter how your BlackBerry uses the blinking blue LED.