1) Buy your ticket by simply sending an SMS to 43210 with EB2011. It will add 17 Euros to your phone bill.
2) In the answer SMS you find a link: this is your Kaywa Ticket
3) At the event, somebody with the Ticket Scanner App will scan your Kaywa Ticket. If it is valid, it will work.
4) If the ticket has already been scanned once, it will from now on be invalid