Have you tried using something like SoapUi, TcpMon, or Fiddler2 to help troubleshoot this? Are the IIS server logs available?
Confirm that are you are in fact sending the correct urls. You can also try turning off chunked encoding. Provided you're using JbossWS Native, there's an endpoint config that you can set that will disable it. It's possible the firewall is rejecting it for that reason