The robots I watched making Legos had no human operators because no human can keep up with them.
This board is built up in sections of one or more operators' positions each.
All the subscribers' lines are connected in order to jacks on the first two or three or four operators' positions, and these connexions are repeated or " multipled " upon each succeeding similar group of positions.
With the adoption of relays the signalling between the subscribers and the exchange became automatic, and, with the introduction of the principle of double and automatic supervision on the cord circuits, it became possible for the operators to tell at any instant the state of a connexion.
The call is controlled by the trunk operators, the junction circuits being equipped in such a manner that the subscribers' signals appear at the trunk exchanges, from which point disconnecting signals are sent automatically to the local exchanges, when the connexions between the trunk and the junction circuits are removed.