Users dont pick departments. They pick a Help Topic.
Help Topics can be anything and can route tickets to specific departments.
Help Topic example:
Printers
New Accounts
Web page edits
The printers help topic could have a custom form where you ask for the make, model, and location of the printer. Or perhaps the inventory ID#. This ticket might go to the Help Desk Department.
New Accounts could have a custom form where you ask for Name: Title: Supervisor: Program/Department staff works for, Employee ID#, Any special access that the staff requires. This ticket might go to the general IT queue.= department.
Web page Edits could have a custom form that asks for the URL of the page that needs to be edited. What the updated text should be, etc. This ticket might go to the development department or your web team department.
To make a form you go to Admin panel -> Manage -> Forms.
To make a Help Topic you go to Admin panel -> Manage -> Help Topics. You can also add the forms here.