Intercom system is a intercommunication device which are used in home ,small building.it is used for communicate to one people to another people.it just behave like a walkies talkies .so many are available in market like audio intercom system,video intercom system.it si also used for security purpose.
We use wireless door bells. I hit button if I need help. I have rrthe buttons taped to my my pwc and walkers. Doug has receivers on each level and in the garage. Works great for us because I can't speak.
intercom systems 
