Do you think there would be a way to have the ringtones of a bunch of cheap phones be a part of a drum kit. One is the snare, one is the high hat etc, and get them to play out some kind of weird beat by calling them? Or they are all on the same #. You could walk into the space and call the number on the wall to interact with it and then the beat, or even score would be performed.
Somehow the music could be conceptualy linked to the idea of this interaction, or it would require other users to call the other numbers to complete the music. You could kind of DJ it.