Can I use 2 iPhones as walkie talkie? (without internet!)

I want to use 2 (or more) iPhones as walkie talkie (i.e. they talk each other without needing internet/voice call).

Of course this should work with wifi, because it doesn't make much sense a to have bluetooth or usb connection for this application...

Solution 1:

There are several apps that will do this in the iTunes Store. The search to use is "walkie talkie". I recommend you look first at Walkie-Talkie - iOS.

Solution 2:

There's an app for that™.

WiChat will allow you to chat with the Bonjour protocol, that is, chatting with people on the local network without connecting to an external server.