I went to check because they looked so old and run down. Athens has plenty of phone booths and as far as I can tell, most of them work. Never seen anyone use them though. These 4 are in the centre, close to the National Museum near Syntagma Square.
I really need to work on my perspective though. When I am lazy it just is all over the place because my main focus is to put colour on paper instead of drawing the outlines.