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);
                }
            }
        }