This is up to you and the platform you are using for live conversations. The handoff example shows one way of doing it switching between two Rasa bots.
One of the main points of that demo is to point out that the handoff should be handled by either the front end UI component or some middleware. It should not be done in the Rasa bot itself. Make sure you don’t put Rasa in the middle of the path between the user and your live chat platform.