/// <summary>
        /// 获取sim卡的IMSI
        /// </summary>
        /// <returns></returns>
        public static string GetIMSINumber()
        {
            string result = "";
            try
            {
                Tapi t = new Tapi();
                t.Initialize();
                Line l = t.CreateLine(0, LINEMEDIAMODE.INTERACTIVEVOICE, OpenNETCF.Tapi.LINECALLPRIVILEGE.MONITOR);
                ControlTapi ctapi = new ControlTapi();
                GeneralInfo gi = ctapi.GetGeneralInfo(l);
               
                result = gi.SubscriberNumber;
                l.Dispose();
                t.Shutdown();

            }
            catch// (Exception ex)
            {
                result = "";
            }

            return result;

        }
加红的Line在什么命名空间?