Siebel Web Service

Hi Team,

we have given one inbound web service to portal system,whenever Siebel is down they are getting below error message is there any way to handle custom message.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"/>

<title>500 - Internal server error.</title>

<style type="text/css">

<!--

body{margin:0;font-size:.7em;font-family:Verdana, Arial, Helvetica, sans-serif;background:#EEEEEE;}

fieldset{padding:0 15px 10px 15px;}

h1{font-size:2.4em;margin:0;color:#FFF;}