//公共变量
//Html网页代码
private string htmlCode = string.Empty;
//运营商
private string corp = string.Empty;
//手机卡类型
private string card = string.Empty;

抓取网页Html代码
///
/// 抓取网页html代码
///
/// URL
///
private static string GetStringByUrl(string strUrl)
{
//与指定URL创建HTTP请求
WebRequest wrt = WebRequest.Create(strUrl);
//获取对应HTTP请求的响应
WebResponse wrse = wrt.GetResponse();
//获取响应流
Stream strM = wrse.GetResponseStream();
//对接响应流(以"GBK"字符集)
StreamReader SR = new StreamReader(strM, Encoding.GetEncoding("UTF-8"));
//获取响应流的全部字符串
string strallstrm = SR.ReadToEnd();
//关闭读取流
SR.Close();
//返回网页html代码
return strallstrm;
}

查询号码归属地
///
/// 查询手机号码归属地
///
/// 网页Html代码
private void QueryLocating(string htmlCode)
{
//创建Xml实例
XmlDocument xmldoc = new XmlDocument();
//加载Xml文档
xmldoc.LoadXml(htmlCode);
//获取Xml文档的根元素
XmlElement root = xmldoc.DocumentElement;

//获取Xml文档的根元素下的所有子节点
XmlNodeList topNode = xmldoc.DocumentElement.ChildNodes;

//子节点集合
XmlNodeList elemList;

//遍历根元素下所有子节点
foreach (XmlElement element in topNode)
{
//根据节点名称获取节点元素值
elemList = root.GetElementsByTagName(element.Name);

switch (element.Name)
{
//判断手机号码格式是否正确
case "QueryResult":
if (elemList[0].InnerText.ToString() == "False")
MessageBox.Show("您输入的手机号码格式有误，请重新输入！", "错误提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
continue;
//手机号码
case "Mobile":
txtMobile.Text = elemList[0].InnerText;
break;
//所属省份
case "Province":
txtProvince.Text = elemList[0].InnerText;
break;
//所属城市
case "City":
txtCity.Text = elemList[0].InnerText;
break;
//区号
case "AreaCode":
txtAreaCode.Text = elemList[0].InnerText;
break;
//邮编
case "PostCode":
txtPostCode.Text = elemList[0].InnerText;
break;
//运营商
case "Corp":
corp = elemList[0].InnerText;
break;
//卡类型
case "Card":
card = elemList[0].InnerText;
//拼接字符串（运营商+卡类型）
txtCard.Text = corp + card;
break;
}
}
}

调用查询方法
///
/// 查询
///
///
///
private void btnQuery_Click(object sender, EventArgs e)
{
if (txtm.Text.Trim().ToString() != "")
{
//抓取网页html代码
htmlCode = GetStringByUrl("http://vip.showji.com/locating/?m=" + txtm.Text.Trim().ToString());

//查询手机号码归属地
QueryLocating(htmlCode);
}
else
{
txtMobile.Text = "";
txtProvince.Text = "";
txtCity.Text = "";
txtAreaCode.Text = "";
txtPostCode.Text = "";
txtCard.Text = "";
MessageBox.Show("请输入手机号码！", "错误提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
}