If you want to add e-mail and SMS services to your application's authentication capabilities, you can do so by creating the interfaces and classes shown here: 

public interface IEmailSender
{
        Task SendEmailAsync(string email, string subject, string message)
  }
  public interface ISmsSender
    {
        Task SendSmsAsync(string number, string message);
    }
public class AuthMessageSender : IEmailSender, ISmsSender
    {
        public Task SendEmailAsync(string email, string subject, string message)
        {
            // We can plug in our email service here to send an email.
            return Task.FromResult(0);
        }
        public Task SendSmsAsync(string number, string message)
        {
            // We can plug in our SMS service here to send a text message.
            return Task.FromResult(0);
        }
    }