Cellular networks regularly operate with trusted devices, which typically are trusted because of the integration of a SIM card therewith. Untrusted devices typically do not interface with a SIM card, and rely on user input through traditional user interfaces for authentication. Recently, the use of hands-free, always-on digital assistant devices have become more common. Such devices typically have only a voice user interface that may be used by a number of people in close proximity to the device. Particular problems arise in such a scenario when a user wants to access a secure service that requires user authentication. Such problems are addressed with multiple techniques described herein.