Improvements in cloud-based speech recognition have led to an explosion in voice assistants, as bespoke devices in the home, cars, wearables or on smart phones. In this paper, we present UIVoice, through which we enable voice assistants (that heavily utilize the cloud) to dynamically interact with mobile applications running in the edge. We present a framework that can be used by third party developers to easily create Voice User Interfaces (VUIs) on top of existing applications. We demonstrate the feasibility of our approach through a prototype based on Android and Amazon Alexa, describe how we added voice to several popular applications and provide an initial performance evaluation. We also highlight research challenges that are relevant to the edge computing community.