Building an App-To-Phone Call Using Android and Flutter

This tutorial guides you through building an Android application that uses Flutter and Vonage Client SDK to make a call from a mobile app to a physical phone number. The application has three screens, and each screen represents a state (LOGGED_OUT, WAIT, and LOGGED_IN). To build the application, you need to prepare by creating a Call Control Object (NCCO), installing the Vonage CLI, setting up a Vonage application, and installing the Flutter SDK. You also need to create a user object and authenticate it using a JWT token. The application uses MethodChannel to communicate between Android and Flutter. To make a call, you need to request permissions for microphone access and use the `makeCall` method to initiate the call. The application can end the call by pressing an "END CALL" button or when the call is answered and ended by the callee. By following this tutorial, you have successfully built an app that makes phone calls using Vonage Client SDK.