In one aspect, a server computer is configured to facilitate operation of a movable barrier operator using voice commands. The server computer includes a processor configured to receive a request for a first rolling voice identifier from a communication apparatus in response to receipt of a voice command of a user requesting a state change of a movable barrier. The processor is configured to send the first rolling voice identifier to the communication apparatus causing the communication apparatus to provide a first physical stimulus to the user based at least in part on the first rolling voice identifier and user account information. The processor is configured to receive a communication indicative of a user voice response to the first physical stimulus and determine whether to instruct the movable barrier operator to change a state of the movable barrier based on the user voice response to the first physical stimulus.