What version of Unity is this?
It would be under the Unity
http://{unityserver}/web/s
a admin website under Call Handlers. Search for the Call Handler in question and check the active schedule on the Profile page for that call handler. Tricky part is you probably won't have just one call handler for this. You'll probably have either two call handlers, one for open hours that allows access to the caller input option for the hunt pilot on Call Manager and the second which would exclude that option. Either that, or you'll have two Call Routing - Forwarded Calls rules, one for open and one for closed that will route to the appropriate call handler. Check the closed call handler in either case to check the caller input options.
What I would do is VNC to the Unity server, open Unity Tools Depot and under the last expandable menu on the left (don't recall the name offhand), double-click the Port Status Monitor. Under the third menu from left (I believe) there is an option for real-time output. Check that box then double click the first four or five ports. Just after 5pm, call your main number and watch the output on the port that answers the call. The output will tell which call handler/mailbox/routing rule is handling the call, which is where you will likely need to go to resolve the issue.
Keep in mind, changing the wrong setting could impact the calls you do want during business hours so please feel free to post any follow-up questions about anything you might find.
