The article demonstrates how to use ASP.NET Core Razor Pages to build an application that collects phone number information on a web form and returns results, including caller ID information. The code uses the Twilio Helper Library for .NET to interact with the Twilio Lookup API, which provides real-time caller information retrieval. The application handles errors generated by the API and includes features such as validating phone numbers and displaying caller name and type if available. The article assumes a basic understanding of ASP.NET Core Razor Pages and C# programming, but provides sufficient guidance for developers to follow along with the tutorial.