USAF has a legacy TFSK (triple fsk) mode, can't recall the name, shows up every few months.
I've seen where a naoc flight will be expecting a data sig on hf and hfgcs will provide it, sometimes even on 11175. This is odd because of all the traffic triple one sees, but a general gets what a general wants I suppose. Normally they use a discreet like 11220 or 11244 for such.