This report was prepared for ComReg, the Irish telecoms regulator, and considers the future award of spectrum in 900MHz band as existing GSM licences expire. This band has recently been liberalised by the EU to allow technologies other than GSM. Three mobile operators have existing GSM licences which expire at different dates, complicating the re-award of this spectrum. The report proposes an auction format to allow licences to be awarded competitively whilst minimising business continuity risks. This is the first auction of this type proposed in the EU. The report can be downloaded here.