There is another Wishlist out there for a similar request.
My suggestion: use FAA approved Air to Air frequencies with the radios and have an option to stream voice traffic from other users within the geographic area and on the selected frequency.
This way if you are transmitting on the frequency and others are within range, they can hear your voice. (Use a Push to talk function to transmit)
This would enable in sim communication with friends for fly ins and events, and also add the ability to announce and hear traffic at uncontrolled airports like in real life.