The objective of this paper is to study whether there are differences in the evolutión of the productivity of the telecommnications firms that operate in liberalised markets as compared to those belonging to their non-liberalised counterparts. Following the proposal of Färe, Grosskopf, Norris and Zang (1994), the productive change of a sample of thirteen telecommunications firms operating in the OECD is obtained on the basis of calculating the Malmquist productivity indexes. There after, this change is broken down into that resulting from technical change and from the changes in the levels of efficiency. The results demonstrate that in the first half of the 1990s the productivity increase of the firms in the liberalised markets exceeded that of those operating in the non-liberalised markets by a significant extent, a tendency reflected in the larger efficiency gains enjoyed by the former. However, the productive change in both type of firms has also been seen to be influenced by circumstances distinct from deregulation and related to changes in the structure of the firms derived from merger and acquisition processes or changes in their capital ownership.

Key words: telecommunications, deregulation, productivity, technical change, efficiency.
JEL classification: C61, D24, L51, L96.