How to send messages sms in c# using serial port and phone used andriod 10

when send SMS message using serial port with android 10 the code don't work but in old version it's work

serialPort1.PortName = "COM4";
serialPort1.ReadTimeout = 2000;
serialPort1.Open();
serialPort1.Write("AT\r");
serialPort1.Write("AT+CMGF=1\r");
System.Threading.Thread.Sleep(2000);
serialPort1.WriteLine("AT+CSCS=\"CDMA\"" + Environment.NewLine);
serialPort1.Write("AT+CMGF=\"" + "774373601" + "\"" + Environment.NewLine);
System.Threading.Thread.Sleep(2000);
serialPort1.Write(messag + Environment.NewLine);
System.Threading.Thread.Sleep(2000);
serialPort1.Write(new Byte[] { 26 }, 0, 1);
System.Threading.Thread.Sleep(2000);
var dd = serialPort1.ReadExisting();
if (dd.Contains("ERRCR"))
{
    MessageBox.Show("faild");
}
MessageBox.Show("Sucsse");
serialPort1.Close();
send();