使用C＃和GSM调制解调器的SMS应用程序正在给出错误

Question

我正在尝试使用GSM调制解调器从此C＃应用程序中将消息发送到电话号码。但这给了这个怪异。

+cme错误：PACM（AP），未重新待办事项

OK

ok ok ok

+CME错误：PACM（AP），not_allowed_slo

OK

+CME错误：PACM（ap），not_allowed_slo

ok ok

+cme ok +cme错误：pacm（ap），not_allowed_slo

ok ok ok ok ok ok 嗨，

错误，

这是我的代码

    private void btnsend_Click(object sender, EventArgs e)
    {
        try
        {
            SerialPort sp = new SerialPort();
            sp.PortName = txtport.Text;
            sp.Open();
            sp.WriteLine("AT" + Environment.NewLine);
            Thread.Sleep(100);
            sp.WriteLine("AT+CMGF=1" + Environment.NewLine);
            Thread.Sleep(100);
            sp.WriteLine("AT+CSCS=\"GSM\"" + Environment.NewLine);
            Thread.Sleep(100);
            sp.WriteLine("AT+CMGS=\"" + txtphone.Text + "\"" + Environment.NewLine);
            Thread.Sleep(100);
            sp.WriteLine(txtmessage.Text + Environment.NewLine);
            Thread.Sleep(100);
            sp.Write(new byte[] { 26 }, 0, 1);
            Thread.Sleep(100);
            var response = sp.ReadExisting();
            if (response.Contains("ERROR"))
            {
                MessageBox.Show("Sending fialed", "Message", MessageBoxButtons.OK, MessageBoxIcon.Stop);
                MessageBox.Show(response);
            }
            else
            {
                MessageBox.Show("Message sent", "Message", MessageBoxButtons.OK, MessageBoxIcon.None);
            }
            sp.Close();
        }
        catch (Exception ex)
        {
        }


    }
}

}