The Keep-alive interval setting is the polling time between the app and your WiFi or cellular service. A longer Keep-alive interval time uses less bandwidth and may increase battery life. A shorter time ensures that Zello is kept running when connected to the service and that the user Status (Available, Busy, or Standby) displayed is the most current.

For most users, the default value should work fine. Increasing the value may improve battery life but the potential downside is your displayed Status may be inaccurate and confuse contacts trying to reach you. For instance, if you have lost connection to the Internet and the Keep-alive interval is not short enough to detect it right away, your Status will continue to show you as "Available" instead of "Standby" (lost Internet connection). 

For optimal benefit, you can reduce the value if you have a power source connected to your device. For example, if you’re using the app in a car with your power adapter plugged in, reducing the value may make your connection more reliable.