First time seeing the picture of the box. I'm surprised it based on the "Next Generation" series. I think the first generation with Kirk would have done better.
The horn/whistle is transmitted over radio freqs (or whatever faster than light system in use) that are picked up by the other ship's communications. Even in the future, the horn/whistle is still considered the fastest way to get someone's attention. Only used intra-solar system where it is more crowded.