The market for telecommunications in Congo has undergone profound changes since Law N°14-97 of May 1997 was enacted because it allowed competition. The ONPT agency (known as SOTELCO after May 2003), which had long remained in a monopoly position, had to share the market with private operators. However, the deregulation movement that has made its way through the sector still grants SOTELCO a monopoly on basic services, thus giving it a structuring role in telecommunications and therefore giving it back its earlier dominant position. In the cellular phone market, the dynamic exploitation of network externalities explains Celtel’s market share vis-à-vis its direct rivals, namely Cyrus and Libertis. The dynamics of the telephone market in Congo is therefore fully explained by the stimulus of network economies and regulations.