来电显示 - 无法获取传入号码

UI 上的标签一直读取"RING RING"，然后返回到空"。但是，它不显示传入的号码，这是我想要的。我试图添加一个 if 函数检查数据中是否有"0"，但由于某种原因仍然不起作用。

以下是我的代码：

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.Ports;
namespace CallerID
{
    public partial class CallerID : Form
    {
        public CallerID()
        {
            InitializeComponent();
            port.Open();
            WatchModem();
            SetModem();
        }
        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);
            WatchModem();
        }
        private SerialPort port = new SerialPort("COM3");
        string CallName;
        string CallNumber;
        string ReadData;
        private void SetModem()
        {
            port.WriteLine("AT+VCID=1'n");
            port.RtsEnable = true;
        }
        private void WatchModem()
        {
            port.DataReceived += new SerialDataReceivedEventHandler(port_DataReceived);
        }
        public delegate void SetCallerIdText();
        private void port_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            ReadData = port.ReadExisting();
            //Add code to split up/decode the incoming data
            if (lblCallerIDTitle.InvokeRequired)
            {
                if (ReadData.Contains('0'))
                    lblCallerIDTitle.Invoke(new SetCallerIdText(() => lblCallerIDTitle.Text = ReadData));
            }
            else
                lblCallerIDTitle.Text = ReadData;
        }
    }
}