cutover

1. (telecommunications) The process of quickly replacing a telephone switchboard, in which the connections are duplicated to the new machine and the original connections are then suddenly disconnected.Examples: "After the heat coils were pulled on the old main frame, the remaining step was merely to pull the wooden plugs on the new switchboard by the strings attached to them (which are bunched together) upon a signal given from the old terminal room, indicating the removal of the heat coils above mentioned. By this means the cut-over was accomplished almost momentarily, the process occupying not over two seconds’ time."countableuncountable

2. (by extension) Any process of quickly replacing a machine or system so as to minimize downtime.broadlycountableuncountable