A large part of Call2Test's value is the IVR service we provide to notify offenders whether they are required to test on a given day. In late 2017 I completed development of ConnectComply, a cross platform native app that allows offenders to check in quickly and securely.
From a development perspective ConnectComply uses the users camera, uploads images to S3, uses geolocation, and push notifications. It provides a fully functional messaging service inside the app. All this is available on Android and iOS (thanks to React Native).