See if "lsof" is available for AIX. It is for Linux, HP-UX and Solaris but I've not used it on AIX.
You can type "lsof -i :<port>"
after it is installed to see what is using that port.
lsof has tons of uses (its name = list open files - sockets are considered file handles) other than the above.
Note there are some things lsof may not show. If you go to its home page and read the faq it will tell you what they are but for most purposes it works just fine.