When you reach the roof, look at your right and you will find two air conditioners. Have someone go one one. Have them crouch and go on it and go to the top right han corner till that person falls very little down, but no off. Then have someone go to the radio and answer it once. Then grab stuff you could use. Then activate it twice and that's it. Then have that person hit Take A Break, The AI will teleport to the people who is active. Then just head back to the security room and relaxe.