read response header information from synchronous message.

We are integrating with a external application (Windows Service Bus) with IB Synchronous operation. We are able to post data and receive response back from external system. For the Error messages the external system provides the details of error as a custom property "Errordescription".  This property is there as element in the fault message structure but comes with message property.  We are not able to see this property in the IB-info that we see in the IB monitor. I used the &Res.IBInfo.IBConnectorInfo.GetNumberOfConnectorProperties() to see all the IB-info from response message. The above expression returns zero. Please suggest me in reading