This male voice is Kevin Cosgrove. He was stuck in the tower while calling. He kept trying to get some support from the emergency services, but they did not be really helpful except try to calm him down. There are some other 911 tapes from two callers in the towers, that have been exhibited since the Moussaoui Trial. I uploaded the full tape so you can hear the whole call, even if it sounds long, you could guess it would even sound longer to that guy.