public static extern int RasDial(int lpRasDialExtensions, string lpszPhonebook, ref DialClass.RASDIALPARAMS lprasdialparams, int dwNotifierType, int lpvNotifier, ref int lphRasConn);
public DialClass()
{
this.Connection = 0;
this.RasDialParams = new DialClass.RASDIALPARAMS();
this.RasDialParams.dwSize = Marshal.SizeOf(this.RasDialParams);
}