To get this achievement simply answer and listen to all the calls that Otis gives you on the walkie talkie during the entire 72-hour mission. You will need to go through most of the 72 hour mode doing the cases for you to receive all Otis's calls. You will not receive calls if you are in the security room, on the roof, or in the area of the scoop/survivors. All scoop calls and case calls are needed (including the calls you get just before the case starts) total of 38 calls.
Five Survivors are also needed for scoop calls: Ronald Shiner, Floyd Sanders, Kindell Johnson, Cheryl Jones, Paul Carson, and Simone Ravendark. Ronald and Kindell both try mutiny and want to take some survivors with them, and floyed needs the 2 from "The Woman Who Didnt Make It" scoop. these survivors are needed to get the scoop calls. The details are on the Survivors and Scoops pages