Germany's telecoms giant said it has appealed to the Constitutional Court to fend off a lower court decision requiring it to allow competitors to look into its books. A federal administrative court had ruled that Deutsche Telekom must reveal how it sets prices when rivals call them into question. The firm's competitors say they would be in a better position to compete with the former monopolist. But Telekom claims opening its books would make it transparent and much less capable of competing. Deutsche Telekom has been accused of price dumping ever since the German telecoms market was liberalized over five years ago. Rival companies have said Telekom's goal is to prevent competition to retain its market share.