Still, Morrow said WiMax is far from dead. He said 600 million people around the world are within reach of a WiMax network and 1 billion will be by the end of this year. "That's a market that's big enough to be around for a long time," he said.

Sprint's Hesse appeared just before Morrow and also cited the possibility of adding LTE. In an on-stage interview at the keynote session, CTIA President and CEO Steve Largent asked Hesse why his predecessors at Sprint had chosen WiMax in the first place. "It was time to market," Hesse said.

"Because of our spectrum position ... we have enough that we can always add other technologies later, but it lets us get in the market quickly," Hesse said. Highlighting that competitive advantage, Hesse added, "If you're interested in 4G, you have one choice."