The act of recording parts of an especially kickass concert to the voicemail of an unfortunate friend unable to make it there due to school, work, or monentary troubles, so they don't feel quite as left out.
A close cousin to the phonecall concert, it allows for convenience and multiple listens.
Jake: Aw man, Matt and Kim
are tearing up the stage with Daylight right now! I feel bad Nick can't be here to see this!
Mike: Oh don't worry about it, I'm leaving Nick a Voicemail Concert!
Nick (the next day): Dude you don't know how much I appreciate this. I don't even care that the audio sucks balls.