I looked at my Trunker log and found 8624 last heard Sept. 2005.
Looks like it's not local to Eastern Ontario so was probably picked up
during enhanced conditions. TGs don't really cross zone boundaries,
but the same TG number can be used in another zone by the same
agency. Not certain, a few special ones may actually be common
across zones.
Anyway, continue to listen and hopefully you can ID it, so it would
be "new" to the database.
Dave