private FeedBackResponse HttpPostRequest(string url, smsPackage pak)
        {
            string responseText = string.Empty;

            try
            {
                var httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
                httpWebRequest.ContentType = "application/json; charset=utf-8";
                httpWebRequest.Method      = "POST";

                using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
                {
                    string json = JsonConvert.SerializeObject(pak);
                    streamWriter.Write(json);
                    streamWriter.Flush();
                }
                var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
                using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
                {
                    responseText = streamReader.ReadToEnd();
                }
            }
            catch (WebException ex)
            {
                responseText = "WebException: " + ex.Message;
            }
            FeedBackResponse fdr = new FeedBackResponse();

            fdr = JsonConvert.DeserializeObject <FeedBackResponse>(responseText);
            return(fdr);
        }
        // Send sms with Feedback service
        public FeedBackResponse SendSMS(List <smsMsg> sms_list)
        {
            FeedBackResponse result = new FeedBackResponse();
            //1. create SMS Package -----------------------------------
            smsPackage pak = new smsPackage(sms_list);

            //2. Post request
            result = HttpPostRequest(this.url, pak);

            return(result);
        }