If he has some help with this, he can contact (via you)the local Fire Department, the 911 operators, the local police and have a note/alert placed in his file. If he ever calls 911 they need to respond immediately. They will put in the file that he has no way to speak and they will just respond. I know that we have friends who's daughter has a trach and they had to contact those local services to let them know that if their address comes up- it has to be immediate response.
Jenn