how to send sms to mobile from webform using SMS API

//code 

 string msg = "hello";
                 string senderusername = "test";
                 string senderpassword = "test123";
                 string senderid = "abc";        
                 string sURL;
                 StreamReader objReader;
                 sURL = "http://info.test.in/API/WebSMS/Http/v1.0a/index.php?username=" + senderusername + "&password=" + senderpassword + "&sender=" + senderid + "&mobile=91" +TxtATSendsms.Text + "&type=1&message=" + msg;
                 WebRequest wrGETURL;
                 wrGETURL = WebRequest.Create(sURL);
                   try
                   {
                       Stream objStream;
                       objStream = wrGETURL.GetResponse().GetResponseStream();
                       objReader = new StreamReader(objStream);
                       objReader.Close();
                   }
                   catch (Exception ex)
                   {
                       ex.ToString();
                   }