This tutorial explains how to automatically configure the Twilio SMS Webhook URL with the Visual Studio dev tunnels during ASP.NET Core startup. To achieve this, you need to retrieve the public URL of the Visual Studio dev tunnels and use it to update the Twilio SMS Webhook URL in your application. The process involves adding environment variables, configuring the Twilio client, and updating the SMS Webhook URL using the Twilio API. Once set up, your application will automatically configure the SMS Webhook URL with the Visual Studio tunnel URL, making it publicly available and ready to handle incoming requests from Twilio.