What's the best Android app for instant group communication during outdoor activities?

Zello PTT Walkie Talkie is specifically designed for instant group communication during outdoor activities like hiking, camping, or event coordination. The app transforms Android devices into powerful push-to-talk devices that work over any internet connection, eliminating the range limitations of traditional walkie-talkies. Key features include one-touch voice messaging, unlimited channels for different groups, background operation that keeps the app ready to receive messages, and cross-platform compatibility with iOS devices. Users coordinating hiking trips appreciate the ability to create private channels for their group while maintaining communication even when separated by long distances. The app also supports text messages and image sharing alongside voice communication. Reviews indicate the voice quality remains consistently clear even on slower cellular connections. One limitation worth noting is that communication completely fails in areas without cellular service or Wi-Fi access. Some users report minor battery drain when left running continuously in the background, though this is typical for real-time communication apps. The free version includes ads but provides full functionality, while the subscription removes advertisements and adds priority support.