You must be on the same WIFI zone to communicate using WIFI Walkie Talkie app.
Multiple can download and use on the same time to communicate. Transmit your voice to all devices which are connected to the same wifi network.
No need to internet connection. For WiFi Walkie Talkie it works without internet connection but you should be connected in same Wi-Fi network.
WiFi Walkie Talkie is a broadcast utility. it is not a secure VOIP application. it works just like a link you need to connect both phones on a same wifi modem.
Are you looking for a free phone call application with out any call charges?. well try out this Free Wifi walkie talkie app and use to communicate with friends, family members on the different floors of same buildings.
Walkie Talkie Functions
=> Broadcast audio on all devices connected on the same wifi modem
=> Touch to Talk or Just Tap on Walkie Talkie.