With this code:

using System;
using System.Linq;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace TEST1
{
  public partial class Form1 : Form
  {
    public delegate void RILRESULTCALLBACK(int dwCode, IntPtr hrCmdID, IntPtr lpData, int cbData, int dwParam);
    public delegate void RILNOTIFYCALLBACK(int dwCode, IntPtr lpData, int cbData, int dwParam);
    public static IntPtr hRil;

    [StructLayout(LayoutKind.Explicit)]
    class RILADDRESS
    {
      [FieldOffset(0)]
      public uint dwSize;
      [FieldOffset(4)]
      public uint dwParams;
      [FieldOffset(8)]
      public uint dwType;
      [FieldOffset(12)]
      public uint dwNumPlan;
      [FieldOffset(16)]
      public byte[] sAddress = new byte[256 * 2];
      //[FieldOffset(528)]
    }

    [StructLayout(LayoutKind.Explicit)]
    class RILSUBADDRESS
    {
      [FieldOffset(0)]
      public uint dwSize;
      [FieldOffset(4)]
      public uint dwParams;
      [FieldOffset(8)]
      public uint dwType;
      [FieldOffset(12)]
      public byte[] sSubAddress = new byte[256 * 2];
      //[FieldOffset(524)]
    }

    [StructLayout(LayoutKind.Explicit)]
    class RILREMOTEPARTYINFO
    {
      [FieldOffset(0)]
      public uint dwSize;
      [FieldOffset(4)]
      public uint dwParams;
      /*[FieldOffset(8)]
      public RILADDRESS rilAddress = new RILADDRESS();
      [FieldOffset(536)]
      public RILSUBADDRESS rilSubAddress = new RILSUBADDRESS();
      [FieldOffset(1060)]
      public char[] sDescription = new char[256 * 2];
      [FieldOffset(1572)]
      public uint dwValidity;*/
    }

    [StructLayout(LayoutKind.Explicit)]
    class RILCELLTOWERINFO
    {
      [FieldOffset(0)]
      uint dwSize;
      [FieldOffset(4)]
      uint dwParams;
      [FieldOffset(8)]
      public uint dwMobileCountryCode;
      [FieldOffset(12)]
      public uint dwMobileNetworkCode;
      [FieldOffset(16)]
      public uint dwLocationAreaCode;
      [FieldOffset(20)]
      public uint dwCellID;
      [FieldOffset(24)]
      uint dwBaseStationID;
      [FieldOffset(28)]
      uint dwBroadcastControlChannel;
      [FieldOffset(32)]
      uint dwRxLevel;
      [FieldOffset(36)]
      uint dwRxLevelFull;
      [FieldOffset(40)]
      uint dwRxLevelSub;
      [FieldOffset(44)]
      uint dwRxQuality;
      [FieldOffset(48)]
      uint dwRxQualityFull;
      [FieldOffset(52)]
      uint dwRxQualitySub;
      /* More minor interesting fields below */
    }

    [StructLayout(LayoutKind.Explicit)]
    class RILRINGINFO
    {
      [FieldOffset(0)]
      public uint dwSize;
      [FieldOffset(4)]
      public uint dwParams;
      [FieldOffset(8)]
      public uint dwCallType;
      [FieldOffset(12)]
      public uint dwAddressID;
    }

    //private static bool done = false;
    private static string result = "";

    [DllImport("ril.dll")]
    private static extern IntPtr RIL_Initialize(int dwIndex, RILRESULTCALLBACK pfnResult, RILNOTIFYCALLBACK pfnNotify, int dwNotificationClasses, int dwParam, out IntPtr lphRil);
    [DllImport("ril.dll", EntryPoint = "RIL_GetCellTowerInfo")]
    private static extern IntPtr RIL_GetCellTowerInfo(IntPtr hRil);
    [DllImport("ril.dll", EntryPoint = "RIL_Hangup")]
    private static extern IntPtr RIL_Hangup(IntPtr hRil);
    [DllImport("ril.dll")]
    private static extern IntPtr RIL_Deinitialize(IntPtr hRil);

    public static void f_notify(int dwCode, IntPtr lpData, int cbData, int dwParam)
    {
      string strMsg = "";

      switch (dwCode & 0x00ff0000) //RIL_NCLASS_ALL
      {
        case 0x00080000: //RIL_NCLASS_SUPSERVICE
          switch (dwCode & 0xff)
          {
            case 0x00000001: // RIL_NOTIFY_CALLERID
              RILREMOTEPARTYINFO rilRemotePartyInfo = new RILREMOTEPARTYINFO();
              Marshal.PtrToStructure(lpData, rilRemotePartyInfo);
              break;
            case 0x00000002: // RIL_NOTIFY_DIALEDRID
              break;
            case 0x00000003: // RIL_NOTIFY_CALLWAITING
              break;
            case 0x00000004: // RIL_NOTIFY_SUPSERVICEDATA
              break;
          }
          strMsg += "SUPSERVICE";
          break;
        case 0x00010000: //RIL_NCLASS_CALLCTRL
          switch (dwCode & 0xff)
          {
            case 0x00000001: // RIL_NOTIFY_RING
              RILRINGINFO rilRingInfo = new RILRINGINFO();
              Marshal.PtrToStructure(lpData, rilRingInfo);
              switch (rilRingInfo.dwCallType)
              {
                case 0x00000000:
                  strMsg += "UNKNOWN ";
                  break;
                case 0x00000001:
                  strMsg += "VOICE ";
                  //RIL_Hangup(hRil);
                  break;
                case 0x00000002:
                  strMsg += "DATA ";
                  break;
                case 0x00000003:
                  strMsg += "FAX ";
                  break;
                default:
                  strMsg += "UNHANDLED ";
                  break;
              }
              break;
            case 0x00000002: // RIL_NOTIFY_CONNECT
              strMsg += "CONNECT ";
              break;
            case 0x00000003: // RIL_NOTIFY_DISCONNECT
              strMsg += "DISCONNECT ";
              break;
            case 0x0000000B: // RIL_NOTIFY_CALLPROGRESSINFO
              strMsg += "CPI ";
              break;
            default:
              strMsg += "SOME ";
              break;
          }
          strMsg += "CALL";
          break;
        case 0x00020000: // RIL_NCLASS_MESSAGE
          switch (dwCode & 0xff)
          {
            case 0x00000001: // RIL_NOTIFY_MESSAGE
              strMsg += "NEW ";
              break;
            default:
              strMsg += "SOME ";
              break;
          }
          strMsg += "SMS";
          break;
      }
      //MessageBox.Show(strMsg);
    }

    public static void f_result(int dwCode, IntPtr hrCmdID, IntPtr lpData, int cbData, int dwParam)
    {
      /*RILCELLTOWERINFO rci = new RILCELLTOWERINFO();
      Marshal.PtrToStructure(lpData, rci);

      result = String.Format("MCC: {0}, MNC: {1}, LAC: {2}, CID: {3}",
          rci.dwMobileCountryCode,
          rci.dwMobileNetworkCode,
          rci.dwLocationAreaCode,
          rci.dwCellID);
      done = true;*/
    }


    public static string GetCellTowerInfo()
    {
      IntPtr res;

      RILRESULTCALLBACK result = new RILRESULTCALLBACK(f_result);
      RILNOTIFYCALLBACK notify = new RILNOTIFYCALLBACK(f_notify);

      res = RIL_Initialize(1, result, notify, (0x00010000 | 0x00020000 | 0x00080000), 0, out Form1.hRil);
      if (res != IntPtr.Zero)
        return ("Could not initialize Ril");
      /*Form1.done = false;
      Form1.result = "";
      res = RIL_GetCellTowerInfo(hRil);
      int i = 10;
      while (i-- > 0 && !Form1.done)
      {
        System.Threading.Thread.Sleep(1000);
      }

      RIL_Deinitialize(hRil);*/
      return Form1.result;
    }
    public Form1()
    {
      InitializeComponent();
      string s = Form1.GetCellTowerInfo();
      //MessageBox.Show(s);
    }

    private void button1_Click(object sender, EventArgs e)
    {
      RIL_Deinitialize(hRil);
      Application.Exit();
    }
  }
}

at line 136 (Marshal.PtrToStructure(lpData, rilRemotePartyInfo);) there is an exception (NotSupportedException) and i don't understand why!!!
Need some help please...........