It may be simplex of ch 9, or even ch 2, or it may be a new frequency altogether. If I happen to catch 833 and/or 837 being dispatched to something on one of my days off, maybe I can go chase it and try to find out. But that may take awhile.
Unless someone has insider information that they can pass on without getting into trouble for doing so.
Have you checked the FCC license website? Are there any new frequencies listed? That may be a clue. We would still need confirmation from someone who actually catches it in use, of course.
John
Peoria