Millicom is positioning itself as a regional challenger in Latin America, while Telefonica, once having a huge footprint on the continent, is stepping away. The challenge of maintaining a multinational MNO with operations in vastly different economies has proven too much for Telefonica, and as it relinquishes most of its operations in South America, Millicom is stepping in to snap up many of them. Millicom’s latest acquisition is Telefonica’s Ecuador unit Otecel. The pair agreed on a deal last week for $380 million. This is the third national asset in the region that Telefonica has agreed to sell to Millicom in the last 12 months. Last month, the Spanish operator agreed to sell its Uruguayan unit to Millicom for $440 million. Last…