 Early switchboards in large cities usually were mounted floor to ceiling in order to allow the operators to reach all the lines in the exchange.The operators were boys who would use a ladder to connect to the higher jacks.Late in the 1890s this measure failed to keep up with the increasing number of lines, and Milo G. Kellogg devised the Divided Multiple Switchboard for operators to work together, with a team on the "A board" and another on the "B".