Gsmcomm.gsmcommunication.commexception ' произошло в gsmcommunication.dll

I'm using ASP.net to send SMS to mobile using GSM Device but unable to send message and getting this error GsmComm.GsmCommunication.CommException in GSMCommunication.dll

Please suggest me how do i resolve this error. I have below code :

using System;  
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
 using System.Linq;
 using System.Text;
 using System.Windows.Forms;
 using System.Data.SqlClient;
 using System.Text.RegularExpressions;

  using System.Runtime.Remoting.Channels;
  using System.Runtime.Remoting.Channels.Tcp;
  using GsmComm.PduConverter;
  using GsmComm.PduConverter.SmartMessaging;
  using GsmComm.GsmCommunication;
  using GsmComm.Interfaces;
  using GsmComm.Server;
  using System.Globalization;

  namespace GSMModem
{
      public partial class Form1 : Form
{
      private GsmCommMain comm;
      private delegate void SetTextCallback(string text);
      private SmsServer smsServer;
      public Form1()
    {
        InitializeComponent();
      }
    TextBox txtMessage = new TextBox();
    TextBox txtDonorName = new TextBox();
    TextBox txtNumber = new TextBox();
    TextBox txtDonorId = new TextBox();
    private void btnExit_Click(object sender, EventArgs e)
    {
        Close();
      }
    private void btnSend_Click(object sender, EventArgs e)
    {
        SmsSubmitPdu pdu;
                    byte dcs = (byte)DataCodingScheme.GeneralCoding.Alpha7BitDefault;
                    pdu = new SmsSubmitPdu("TESTING MESSAGE", "03325483575", dcs);
        comm.SendMessage(pdu);
 }

    private void Form1_Load(object sender, EventArgs e)
    {
        cmbCOM.Items.Add("COM1");
        cmbCOM.Items.Add("COM2");
        cmbCOM.Items.Add("COM3");
        cmbCOM.Items.Add("COM4");
        cmbCOM.Items.Add("COM5");
        cmbCOM.Items.Add("COM6");
        cmbCOM.Items.Add("COM7");
    }

    private void btnConnect_Click(object sender, EventArgs e)
    {
        if (cmbCOM.Text == "")
        {
            MessageBox.Show("Invalid Port Name");
            return;
        }
         comm = new GsmCommMain(cmbCOM.Text , 9600, 150);
        Cursor.Current = Cursors.Default;
        bool retry;
        do
        {   retry = false;
            try
            {   Cursor.Current = Cursors.WaitCursor;
                comm.Open();
                Cursor.Current = Cursors.Default;
                MessageBox.Show("Modem Connected Sucessfully");
            }
            catch (Exception)
            {   Cursor.Current = Cursors.Default;
                if (MessageBox.Show(this, "GSM Modem is not available", "Check",
                    MessageBoxButtons.RetryCancel, MessageBoxIcon.Warning) == DialogResult.Retry)
                    retry = true;
                else
               { return;}
           }
        }
        while (retry);

    }

    }
      }