I don't know how much they're charging, but in violent cities it sounds useful. You can have the exact location of a gunshot and dispatch an officer in a matter

I don't know how much they're charging, but in violent cities it sounds useful. You can have the exact location of a gunshot and dispatch an officer in a matter of seconds, and microphone arrays should be pretty cheap. Together with cell-id positioning it's a powerful tool for investigation: you can have the exact location/time of the shot and exactly who was nearby that that moment. The alternative for violent areas is relying on witnesses to both dispatch help and confirm date and place of gunshots.