Hi Josh,
Depending on how the calls are coming into UC (forwarded, or direct) you'll want to take a look at the Call Routing rules and see where the calls are being sent. If you're unable to determine where the call is being routed to, use either RTMT or download the remote port monitor tool from ciscounitytools.com (there is a couple configuration settings you need to perform in the help file for the tool to work) and you can see what call handler/greeting is being played and then go to that object and configure the after greeting actions for it.
Hope that helps,
Brad
