When evaluating coaster pagers, prioritize transmission range, typically requiring 500 to 1,000 meters in open areas to ensure coverage across large venues. Look for systems utilizing FM (Frequency Modulation) technology rather than AM to minimize signal interference. The battery capacity should be at least 200-300mAh, providing a standby time of 24-48 hours. Additionally, ensure the pagers feature IP32 or higher water resistance to protect against accidental spills common in restaurant environments.