private void btnBlindTransfer_Click(object sender, EventArgs e)
        {
            GetDialableNumberForm gdf = new GetDialableNumberForm("Transfer");

            if (gdf.ShowDialog() == DialogResult.OK)
            {
                if (gdf.Number.Length > 0)
                {
                    _call.BlindTransfer(gdf.Number, 0);
                }
            }
        }
        private void btnDial_Click(object sender, EventArgs e)
        {
            GetDialableNumberForm gdf = new GetDialableNumberForm("Dial");

            if (gdf.ShowDialog() == DialogResult.OK)
            {
                if (gdf.Number.Length > 0)
                {
                    _call.Dial(gdf.Number, 0);
                }
            }
        }
        private void btnPark_Click(object sender, EventArgs e)
        {
            GetDialableNumberForm gdf = new GetDialableNumberForm("Park");

            if (gdf.ShowDialog() == DialogResult.OK)
            {
                if (gdf.Number.Length > 0)
                {
                    _call.Park(gdf.Number);
                }
                else
                {
                    _call.Park();
                }
            }
        }