From Inner Four:
Wifi walkie talkie uses a wifi connection to broadcast speech to other wifi wakie talkies on the same wifi network. Just like with a real Walkie talkie, You don't have to connect to the other walkie talkies first because broadcasting does not require a connection. This makes the app much easier to use.
This application ONLY WORKS with iPhones running O.S. 3.1 or greater.