Erlang, the son of the local schoolmaster, learnt to read upside down, sitting opposite his elder brother. He graduated from U Copenhagen in 1901 and joined the Copenhagen Telephone Company in 1908, with whom he remained for the rest of his career. His first publication was entitled The Theory of Probabilities and Telephone Conversations and his subsequent research involved many trips down the manholes of Copenhagen.

http://www.apprendre-math.info/history/photos/Erlang_4.jpeg Photograph.