SMS gateway programming

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.IO;


 string ozUser, ozPassw, sender, reciver, route1, sms1;
   protected void Page_Load(object sender, EventArgs e)
    {
     
        
    }

 protected void Button1_Click(object sender, EventArgs e)
   {

       ozUser = "na";
       ozPassw = "na";
       sender = "na";
       reciver = TextBox4.Text;
       route1 = "TA";
       Label1.Text  = TextBox1.Text + "\n" + TextBox2.Text + "\n" + TextBox3.Text;


       string URL = "http://url of api/httpapi/smsapi?uname=" + ozUser + "&password=" + ozPassw + "&sender=" + sender + "&receiver=" + reciver + "&route=" + route1 + "&msgtype=" + 1 + "&sms=" + Label1.Text;


       HttpWebRequest request = (HttpWebRequest)WebRequest.Create(URL);
       request.Method = "GET";
       request.ContentType = "application/json";
       request.ContentLength = 0;// DATA.Length;
       WebResponse webResponse = request.GetResponse();
       Stream webStream = webResponse.GetResponseStream();
       StreamReader responseReader = new StreamReader(webStream);
       string response = responseReader.ReadToEnd();
       Console.Out.WriteLine(response);
       responseReader.Close();
   }