The article demonstrates how to use Twilio Lookup to obtain carrier information associated with a phone number, using ASP.NET Core Razor Pages and the Twilio Helper Library for .NET. The code initializes an instance of the Twilio client using credentials stored as environment variables, then uses the `PhoneNumberResource` class to make an asynchronous call to the API to validate the phone number and retrieve carrier information. If the value of `PhoneNumberRaw` can be validated for `CountryCodeSelected`, the API returns the phone number formatted in the appropriate national format and E.164 format. If carrier is requested from the API, it returns a dictionary object that may have an error code set. The article provides examples and explanations of how to use the Twilio Lookup API with the Twilio Helper Library for .NET, including handling errors returned through the API and in error codes included in the retrieved information.