Send SMS with Twilio 5.x helper library with manually created TwilioRestClient

Program.cs

using System;
using Twilio.Clients;
using Twilio.Rest.Api.V2010.Account;
using Twilio.Types;

namespace ConsoleApplication32
{
    class Program
    {
        static void Main(string[] args)
        {
            // Your Account SID from twilio.com/console
            var accountSid = Environment.GetEnvironmentVariable("TWILIO_ACCOUNT_SID");
            // Your Auth Token from twilio.com/console
            var authToken = Environment.GetEnvironmentVariable("TWILIO_AUTH_TOKEN");

            var client = new TwilioRestClient(accountSid, authToken);

            var message = MessageResource.Create(
                to: new PhoneNumber("+15558675309"),
                from: new PhoneNumber("+15017250604"),
                body: "Hello from C#",
                client: client);

            Console.WriteLine(message.Sid);
            Console.Write("Press any key to continue.");
            Console.ReadKey();
        }
    }
}