Samsung M520 Owner's Manual page 46

Note: Display indicators help you manage your roaming charges by letting you
know when you're off the home network. (For more information, see
Section 2D: Controlling Your Roaming Experience on page 91.)
20 Section 2A: Phone Basics
Indicates that a voice memo or video is playing.
Indicates that media has been uploaded to an online album or
folder.
Indicates that voice captioning is enabled and that audio is
currently being recorded.
Indicates that Bluetooth technology is active and enabled
(actual icon is black).
Indicates that the Bluetooth device is connected (actual icon is
blue).
Indicates that the Bluetooth device is hidden (actual icon is
gray).
Indicates that your phone is using a microSD memory card.