The Party Line app is an audio-only solution to help users avoid Zoom fatigue by reducing cognitive resources required during calls. It was created as part of Daily's focus on supporting audio-only apps with APIs. The React Native version of the app, called Party Line, allows users to join or create audio calls and includes features like participant management, moderation, and muting. The app uses the react-native-daily-js library and follows a component-based structure, including the CallProvider component that manages global app state and handles actions related to joining and leaving calls. The app also addresses device permissions by setting videoSource to false when creating the local call object instance. To get started with Party Line, developers need basic React Native knowledge and can follow tutorials and resources provided by Daily for further guidance.