/// <summary>
        /// STOP DLR Retriever 
        /// </summary>
        private void StopDeliveryReportRetriever()
        {
            if (deliveryReportRetriever == null)
            {
                return;
            }

            deliveryReportRetriever.Stop();
            deliveryReportRetriever = null;

            if (LOGGER.IsInfoEnabled)
            {
                LOGGER.Info("Delivery Report Retriever is successfully stopped.");
            }
        }
        //*************************SMSMessagingClientImpl private******************************************************************************************************************************************************
        /// <summary>
        /// START DLR Retriever
        /// </summary>
        private void StartDeliveryReportRetriever()
        {
            if (this.deliveryReportRetriever != null)
            {
                return;
            }

            this.deliveryReportRetriever = new DeliveryReportRetriever();
            int intervalMs = Configuration.DlrRetrievingInterval;
            this.deliveryReportRetriever.Start(intervalMs, this);

            if (LOGGER.IsInfoEnabled)
            {
                LOGGER.Info("Delivery Report Retriever is successfully started.");
            }
        }