communication question.

I’m trying to find a way for my wife and I to talk while we’re out on the trails. I’ve looked at various communicators for our helmets that would run anywhere from $200-$500 for us to talk. We’re cheap and honestly it’s not that important to buy something when we ride no more than 20 yards from each other. In the past I’ve called her on my phone and we just talk with the headsets that come with our phones, but we often ride in areas that do not always have cellular service. We both have iPhones I was wondering if anyone knows of an iPhone app that uses Bluetooth to talk to each other. I’ve seen a couple apps on the app store that allow this and just want to see if anyone has tried them and what their experience has been. I would also like to see if there is an app that allows us to listen to music when nobody is speaking, like some of those higher end communicators. Any help would be greatly appreciated!!