All airliners I have been on have a hot mic type interphone system. But a lot of airlines do not have boom type microphones. It seems that most European airlines use headsets with boom mics, and most American airlines use loudspeakers and hand mics. I have always wondered why. I would have thought that it was safer to use a boom mic?
Caught me out last year. I was doing my first engine run on a MH B777, and put on the headset and tryed to talk to the tower. Then I found out that the headset was only a mic, and I had to turn on the speakers to listen to the replies.
Are there laws out there for different areas about what you have to use?