Your iPhone already comes with everything you need to stay connected. With the Talk Now! Walkie Talkie app, you can use it to connect with your friends and family members over open or private channels. It lets over 20 people be on the same channel at once. You can limit access only to those who have an invitation code when you need some privacy.
This app has a simple interface with customizable color. With push to talk function, you can connect with your friends fast. Dragon Free Games is the developer behind this app. You can find out more here.