This awesome installation made by James Theophane uses 50 programmed mobile phones, each with their assigned tone. So how'd they get all those phones to play the right tune at the right time? The program on the phone consisted of two parts: one registering with a web service - logging the fact that it was still alive and its current IP address, and two a User Datagram Protocol listener - listening for commands from the controller over the network. The controller was written to read the midi file of the Carol and send the individual notes to individual phones at the right time.
Behind The Scenes