Getting information from SOAP call in R/3 using RFC adapter

I have following scenario:

R/3 (RFC) > XI (SOAP) > WebService

I want to know within the R/3 if the call to the webservice fails (Server not available, etc), that there is a problem.

Is there any exception code or way to fill the exception with a return code? I have tried to map a exception, but it will only be created, if the WS-Application creates the exception not if an error occurs in XI or the AF.

Best regards

Helmut