C# obtain return code from called program

Question

I have a C# 2008 application that does not have access to the return code of the second program it is calling . The second program that is called is a web service and the return code is in a proxy.
 
 Thus can you tell me the best way on how to obtain the return code from the proxy? Can you point me code and/or point me to a refernce on how to solve this problem?