For future reference, you do not need to waste a license to accomplish this task. There are many places where voicemail and lamps are required that are either not possible or difficuly to work with. It is usually when calls are presented to groups (Hunt/ACD/Ring) and voicemail is required either afterhours or when no answer.
The solution is to create a terminating DN as the first hop before routing to the Group and/or voicemail. As you've discovered, a hotdesk user can be configured as this teminating DN. The downside of this is that each hotdesk user consumes licensing. If only 1 instance is required, no problem but if several or many are required it can be expensive.
On a typical system I use 1 Phone license to create an extension (5224 with dual PKM) This phone would have 120 routable DN's via the Prime ext and key programming. These keys can also be used to create the BLF's necessary for 5550 consoles. Each key can be programmed with a DN in much the same manner as your hotdesk solution with much lower cost.
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Occam's Razor - All things being equal, the simplest solution is the right one.