From http://www.live8live.com/tickets.shtml

Details of the text number and competition will be announced on the 6th June - via all UK radio stations & BBC Television. No entries will be accepted before 00:01 on the 6th June.

Each entry costs £1.50* plus your operator's standard text charge.

The competition will close at midnight on the 12th June and winners will be chosen at random by computer and notified by text message after the 13th June with details of how they can collect their tickets - either online or from collection points around the UK.

Due to the tight deadlines we are working to, you will need to be able to collect your tickets within ten days of notification of winning, otherwise you will forfeit them.