UDP is a low-level networking protocol. No specification at all for the information that it carries. It's like an old-school radio: just throw something out to the world and hope it gets there. No guarantee of anything.
Though it usually does work on a local network. Real-time controls often use it because it's simple, easy to get right, and there's another update coming in 100ms anyway, or whatever the interval is. I've done that myself in a custom app to send commands to a digital mixing console (volume5 = -6dB) and receive the status back (meters, etc.).
Now, what again are you doing with this equivalent to a walkie-talkie?
