hmmmm 2.2.x didn't make this easy to run down... can you search the call handlers by extension and find a match? It may be that the primary call handler for a subscriber is tagged as a "normal" handler now and it's showing up there on it's own (i.e. it's not considered an orphan).
If you know the alias of the subscriber that used to own that call handler you can go in to the Exchange administrator under the unity folder, drill down into the call handlers folder under that and go delete the primary call handler manually (it'll have an alias of "ch_" - but be real careful to get the right one...