The machine is real, the person's voice is also real, but they combine to produce a recording, which is also real, just not in real time.
i think various practices adopt their own solutions to the tiresome fact that patients will insist on disturbing their peace and quiet with phone calls about being ill.
My MIL's practice has one of the GP's who is far too fond of the sound of his own voice, giving a message that lasts nearly two minutes before you get the keypad options to go to whichever department is going to ignore you until you lose the will to live.