Time Travel, although I would love to believe in it could be ruled out by an article I stumbled upon today.
It consists of a man by the name of Charles E. Alden. He claimed to have invented " The Pocket Phone: A telephone which could be carried in a pocket "
Mind Blown! lol
Research on Charles E. Alden concluded that he mysteriously vanished and of course his "pocket phone" was never released or discovered.
So, could it be him, or maybe someone who had obtained his invention that is seen in that scene in the Chaplin movie?
Just something to think about. I think this makes better sense than the theory of someone walking around with a horn used to amplify sound, as the person looks to be engaged in a conversation.
**Edited to add link**
Edited by KovenantNebulus, 01 October 2013 - 10:54 PM.