OECD, Directorate for Science, Technology and Innovation, Committee on Digital Economy Policy, Working Party on Communication, Infrastructures and Services Policy, Wireless Market Structures and Network Sharing (DSTI/ICCP/CISP(2014)2/FINAL) (Jan. 8, 2015) (full-text).
This report finds that in countries where there are a larger number of mobile network operators (MNOs), there is a higher likelihood of more competitive and innovative services being introduced. Particularly, a larger number of operators is often the source for innovative offers that challenge existing market wisdom and practices. As a result, some call these MNOs the "challengers." The effects on a market, of course, are not limited to actions by "challengers" as incumbent operators respond with their own offers and react on price, with the introduction of new services as well as quality.
This report also finds that in markets introducing new players or maintaining at least four operators, investments in new network infrastructure increase and are pulled forward by existing operators, to defend against challengers. The report does not find extraordinary reductions in retail revenues for operators in most of these markets. Instead, it appears that mobile operator retail revenues have been remarkably stable over the last decade, though there are exceptions.