A user initiates a voice request to perform an operation with an external service and provides a voice credential for the operation. A determination is made as to whether the user has used a separate device from that which is associated with the voice request to log into the external service within a preceding amount of time before the voice request and/or within a succeeding amount of time following the voice request. If the user has such a login with the external service, the voice operation is processed on behalf of the user with the external service using the voice credential; otherwise the voice request is ignored.