Everyone knows the old 'can and string' phone.
But does it realy work? The answer is yes.
It works with cans but plastic or paper cups work better. All you have to do is make sure that the string is straight and tight.
Someone actually patented the invention of the paper cup asnd string phone in 1980. But a few years ago the patent wore off and the world was free to build paper cup and string phones yet again.
