Launching and stimulating competition in telecommunications markets is an important policy goal. It contains two elements: to encourage entry and to make competition effective such that consumers benefit. The first one requires that entrants can make profits after investing in infrastructure so...

In many markets, user benefits depend on participation and usage decisions of other users giving rise to network effects. Intermediaries manage these network effects and thus act as platforms that bring users together. This paper reviews key findings from the literature on network effects and...