How do I use a modem to call a phone and play a wave file over it

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VB

I want to call a mobile through voice modem and play a wave file over it my code is here !! Its not working !!just while looping but no answer or no error! when I resubmit request its detect error "Access to the port 'Com1' is denied"

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.IO;
using NAudio.Wave;
using System.IO.Ports;
using System.Threading;

namespace mearge
{
    public partial class Form3 : Form
    {
        public Form3()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {

            System.IO.Ports.SerialPort comPort;
            comPort = new System.IO.Ports.SerialPort("Com1",9600, System.IO.Ports.Parity.None, 8, StopBits.One);
            comPort.DtrEnable = true;
            //Switch to Voice Mode
            comPort.Write("AT+FCLASS=8" + System.Convert.ToChar(13).ToString());
            //Call Number
            comPort.Write("ATDT997448***" + System.Convert.ToChar(13).ToString());
            //Enter Voice-Transmission Mode
            comPort.Write("AT+VTX" + System.Convert.ToChar(13).ToString());
            bool MSwitch = false;
            byte[] buffer = new byte[20000];
            FileStream strm = new FileStream(@"D:\943461101.wav", System.IO.FileMode.Open);
            MemoryStream ms = new MemoryStream();
            int count = ms.Read(buffer, 44, buffer.Length - 44);
            BinaryReader rdr = new BinaryReader(strm);
            while (!MSwitch)
            {
                byte[] bt = new byte[1024];
                bt = rdr.ReadBytes(1024);
                if (bt.Length == 0)
                {
                    MSwitch = true;
                    break;
                }
                comPort.Write(bt, 0, bt.Length);
            }
            strm.Close();
            strm.Dispose();


        }
    }
}