Handle Keypad Input (DTMF) with Java

You will need a Vonage account to complete this tutorial, which includes a phone number and API key and secret. You'll use Gradle to manage your dependencies and create a new Java project, then set up routes for handling incoming calls and user input using the Spark framework. The application responds with an NCCO instructing Vonage to speak back to the caller or capture user input, which is then sent to Vonage for processing. You'll also use ngrok to expose your local application to the internet and configure your Vonage account to link your phone number to the application. Once set up, you can test your application by making a call to your Vonage number and interacting with it using your keypad.