A pre-registration procedure is utilized to create a user profile for a user of a multi-factor authentication (“MFA”) service. A client application installation procedure is utilized to install a client application on a computing device that is to be utilized as an authentication factor for the MFA service. A computing device enrollment procedure is utilized to enroll the computing device on which the client application was installed for the MFA service. A voice enrollment procedure is utilized to create a voice print for the user of the computing device that is to be utilized as an authentication factor for the MFA service. An authentication procedure is utilized to provide multi-factor authenticated access to a service, such as an online service that provides access to sensitive account information.