Jones 50-line switchboard, 1879.
© Science Museum / Science & Society Picture Library
This American plug and cord switchboard was made by Jones Bros of Cincinnati, United States and installed in Norway by the Bell Company in 1880. The first switchboards had no more than 50 lines per board as this was the most one operator could control. Exchanges with more than 50 subscribers had to have a number of switchboards and operators. If a caller required a number which did not operate from the same switchboard, the two operators had to confer first to see if the required number was free, and then make the exchange. The increase in use made this situation unworkable in the early 1880s and it was only resolved with the introduction of the multiple switchboard in 1884.