What is Zello?
Zello is a free walkie-talkie app for smartphones, tablets, laptops, and desktop computers. The app requires an Internet connection to function correctly, whether via Wi-Fi or mobile data. Unlike standard calls on your device, Zello connects you to fellow users and radio channels, letting large groups talk regardless of distance.

How to get started with Zello
Install the Zello app. Open up iTunes or Google Play and install Zello.
This shouldn’t take long if you have a reliable connection.
Sign up for an account. If you don’t have an existing Zello account, you’ll need to make one from scratch. The process is quick and only requires a username, email address, password, and an optional phone number. You can’t change your username after creating an account, so make sure it's spelled correctly. Add channels from this link.