23. A method comprising: at an electronic device: receiving a plurality of voice commands from a user; generating a plurality of voice samples of the user from the plurality of voice commands; while the device is in a locked state, receiving non-voice authentication information from the user to put the device into an unlocked state; in response to authenticating that the user is an authorized user of the device, transmitting the plurality of voice samples to a voiceprint service for generating a voiceprint based on the plurality of voice samples; receiving a speech input, the speech input including a command associated with a restricted feature of the device; determining whether the speech input was spoken by an authorized user of the device, the determining including comparing the speech input to the generated voiceprint; processing the speech input to identify the command; and upon determining that the second speech input was spoken by the authorized user, providing access to the restricted feature of the device according to the command, where the method is performed by one or more processors of the device.
24. The method of claim 23 , wherein the plurality of voice samples are transmitted in batches to the voiceprint service in response to the device experiencing low resource usage.