A mid-sized manufacturing company just completed its first incident response tabletop exercise. During the debrief, the team notes that when a simulated ransomware event was declared, responders wasted nearly 45 minutes trying to determine who to notify, in what order, and how to reach after-hours contacts because several phone numbers were outdated and no backup contacts existed. Which preparation-phase artifact should the IR team prioritize updating to directly resolve this specific gap before the next exercise?