Single-elevator control and group control are usually separate. In many systems, the group controller's authority is limited to remotely pushing the buttons in each elevator in each elevator. Thus, the group controller has no safety responsibilities.

All the hall calls (from the buttons outside the elevator) go to the group controller, which controls dispatch policy. Early systems, such as the Otis Autotronic, used analog computer components to set dispatch policy. The newest ones use machine learning.

If you set an elevator to "independent service" (this is a key switch in most elevators) it disconnects from the group controller and only obeys its own cab buttons. This is used when you need a service elevator, but not often enough to have a dedicated one. The group controller is not necessary for basic elevator operation.