This tutorial provides a step-by-step guide on how to set up a conference call using ASP.NET Core and NancyFX, allowing multiple people to join the same call. The process involves creating an ASP.NET Core app, setting up a Vonage voice application, and configuring the application to handle incoming calls using NancyFX. Once configured, the application will respond with a NCCO that guides the user through the conference call process, including greeting them and adding them to the conference. To test the application, it requires linking a Vonage phone number, setting up an answer URL using Ngrok, and running the app locally before calling the TO_NUMBER to initiate the conference call.