It's also a quick way to raise some cash. Reliance recently sold a 5 percent stake in its tower unit to a group of international investors for $337.5 million, valuing the business at $6.7 billion. (See Reliance Sells Tower Stake.) Bharti, which has a larger network, quickly said it would be selling a stake in its new tower unit, too. And last week, IDEA Cellular's board approved the formation of a separate company for its network infrastructure.