AT&T CEO Randall Stephenson has urged the Federal Communications Commission to find more frequencies for mobile broadband. “We have to do something to free up more spectrum,” Stephenson told a CEO forum at the Brookings Institution, a US think tank. He shared the panel with FCC chief Julius Genachowski who said the regulator is looking at ways to free up additional airwaves including auctioning frequencies used by TV stations and offering the broadcasters a share of the proceeds.