Kind of a unique idea. This company is using iPhones to make ad hoc intercom systems. This all happens over Wifi, and in fact you could use much cheaper iPods for that scenario. Where it really gets cool is you can also do intercom over cellular data.
Say you’re doing a small mobile at a basketball game. Everybody is on a wifi network in the gym, but you have an outside cameraperson shooting live scenics leading into commercial breaks. That outside cameraperson can be cued with the same intercom, over cellular. Essentially, that outside cameraperson could be in the capital of Mongolia and still be on intercom (although I’m not sure what the LTE signal is like in Ulaanbaatar).
The system scales, and can be tied into traditional intercom systems too.