Voxer. It's a 'walkie-talkie' app which is really handy when driving, and when you don't feel like typing out long text messages. Doesn't use a lot of data and is really quick in sending messages (almost live when app is open)
why stereo?
dispatch means the audio is being sent out of a group of people? like a wrecker service? how's the audio being received on those devices?
i think if you're more specific, you may get better responses.
Personally, I would suggest you check out voxer for mobile smart phones http://voxer.com/
voxer is a cool app. it's like... voice sms, or a walkie talkie haha. its free as well and seems to work well with friends who aren't keen on texting, but don't want to call either. it's like an in-between app. i think voice texting is the best way to describe it.
some of my friends overseas use it too, and its a good way to hear them without having to pay for the long distance call.