The activation of lights of a mobile communication terminal is controlled with information in music data files, such as SP-MIDI files. The music data files contain note events informating the terminal to play a note of a particular instrument. Light configuration messages are added to the SP-MIDI file. The light configuration messages contain information mapping the activation position, -color and -intensity to the note events. The mobile terminal is provided with an editor application for creating and changing light configuration messages. The light configuration messages can also be created and changed with a light configuration program on a PC. The light configuration messages can be tested on a PC with a MIDI editor program provided with a plug in application for emulating the mobile communication terminal.