Irish music fans will not be able to go to London's Live 8 concert on July 2.
A text message lottery for the tickets is to be held tomorrow, but will not be accessible from Ireland.
The 150,000 tickets for the London concert will be awarded through an O2 UK-run text lottery, starting at 8am.
O2 Ireland is a separate franchise and is not part of the British O2 operator's system, which is why Irish customers are unable to participate in the draw.
Listeners to BBC and commercial radio stations across Britain will be asked to answer a multiple-choice question and to send a text message to a number given at the time. The winners are eligible to get two tickets to the show.
The lottery question will also be shown on big screens in seven cities across Britain, and shown live on TV.
The free event will be held in London's Hyde Park with concerts in Philadelphia, Paris, Rome and Berlin.
The original Live Aid concerts, in July 1985 in Wembley Stadium and JFK Stadium, Philadelphia, raised £40m (€59.3m) for famine relief in Africa.