My suggestion would be to have the VRU ask if the caller if they are calling about a previously reported issue. If they respond that it is (push 1, say “yes”, etc) then they would then be prompted to enter their ticket number. The ticket number would then key the VRU to route the call to the appropriate skilled Service Desk.

If the user doesn’t have a ticket number, they are routed to an Unskilled Service Desk that searches the Incident database for their ticket and updates it with their comments/questions.

It should become apparent to the users that knowing the ticket number gets them routed to skilled analysts. Not knowing their ticket number gets them routed to someone who will simply make notes.

This all assumes that your VRU can integrate to the Incident database in such a way that the VRU can route a call based on the categorization of a queried ticket number.