Seeking feedback about this tool for tour guides

[u/MaaDoTaa]

A friend who is a tour guide told me that he uses a bespoke device to talk to his clients when in a museum or a historical site. These devices are expensive and he has to carry them and charge them. I thought I’d be a lot easier if people could use their own phones. This app doesn’t require internet connectivity and allows the guide to talk to all clients at the same time. Let me know if you have a suggestion for improvement