GSM Modem, Exception: No data received from phone after waiting for 30046 ms

Question

I have made a Windows Services which after 10 ms gets received unread messages from Modem through GSM Library. Every thing is going ok. But sometimes randomly it logs "No data received from phone after waiting for 30046 ms" exception and sometimes it logs "No phone connected" exception.

This is my code.

try {

            comm = cs.comm;

            try
            {
                if (!comm.IsOpen())
                {
                    comm.Open();
                }
            }
            catch (Exception ex)
            {
                Utility.LogMessage(ex.Message);
            }

            try
            {
                DecodedShortMessage[] messages = comm.ReadMessages(PhoneMessageStatus.ReceivedUnread, PhoneStorageType.Phone);

                foreach (DecodedShortMessage message in messages)
                {                                                
                  //Read sms   
                }
            }
            catch (Exception ex)
            {
                if (ex.Message != "Port not open.")
                {
                    Utility.LogMessage(ex.Message);
                }
            }

            comm.Close();
        }
        catch (Exception ex)
        {
            Utility.LogMessage(ex.Message);
        }