What's the best iOS app for instant voice communication with a team during events?

Zello Walkie Talkie is particularly well-suited for event coordination where instant voice communication is essential. The app transforms iOS devices into walkie-talkies that work over cellular data or Wi-Fi, allowing event staff, volunteers, or security teams to stay connected without the range limitations of traditional radios. Key features include one-touch broadcasting to entire groups, private channels for specific teams, and the ability to see who's currently active and available. The app maintains connection even when running in the background, ensuring important communications aren't missed during hectic event situations. However, some users note that finding available channel names can be challenging due to the app's popularity, and the free version's channel discovery features have become less intuitive over time. Still, for organized events where channels are pre-established, Zello provides reliable instant communication that eliminates the need for expensive radio equipment. The voice quality is generally clear, though occasional lag can occur during poor network conditions. For event planners, festival organizers, or any team needing instant group communication across a wide area, Zello delivers practical functionality that's hard to match.