HTTP API SMS gateway in C#

using System;
using System.IO;
using System.Net;
using System.Text;
namespace SMSGateway
{
    class Program
    {
        static void Main(string[] args)
        {
            const string userId = "UserName";
            const string password = "Password";
            const string phoneNo = "Enter Mobile Number";
            const string serviceId = "WebSMS";
            const string message = "Test SMS From bulksms";
            const string url = "http://bulksms.w2wts.com/API_SendSMS.aspx?User=" + userId + "&passwd= " + password + "&mobilenumber=" + phoneNo + "&message=" + message + "&sid=" + serviceId + "&mtype=N&DR=N";
            string response = SmsAlerts.GetResponse(url);
            Console.Write(response);
            Console.ReadKey();
        }
    }
    public class SmsAlerts    {
        public static string GetResponse(string url)
        {
            var request = (HttpWebRequest)WebRequest.Create(url);
            request.MaximumAutomaticRedirections = 4;
            request.Credentials = CredentialCache.DefaultCredentials;
            var response = (HttpWebResponse)request.GetResponse();
            Stream receiveStream = response.GetResponseStream();
            var readStream = new StreamReader(receiveStream, Encoding.UTF8);
            string responseStatus = readStream.ReadToEnd();
            response.Close();
            readStream.Close();
            return responseStatus;
        }
   
    }
}