The ability to build an LTE network, which will offer data speeds up to 10 times those now available, will be a key competitive advantage in Austria's hard-fought telecoms market.
The country's four operators are engaged in a price war as they fight over a population of just 8.4 million, with all-inclusive, no-strings offers available for as little as 7 euros per month.
T-Mobile said on Wednesday it had lodged an appeal on December 31 with Austria's higher administrative court against the decision of the country's telecom control commission, the TKK, for the transfer of frequencies that will accompany the merger.
It said it had asked for the transfer to be put on hold while its legal case is being heard. It said it expected the court to decide within days on whether to grant an injunction in the case, which it thought could last until March or April.
A court spokesman said the court had not yet received the appeal.