I have always wondered. I do carry a grunt tube and use it. But have never brought one in or think I've heard mulie bucks or does.There's very little deer hunting in November here in Wyoming so we don't get to hunt the rut.
So much has been written about and products sold for elk and whitetails, but not mulies. My grunt tube does say "And works for mulies". Not really made for it.
Is their voice higher or lower than whitetails?

I have a call from Elk, Inc made for mulie does/fawns, and have gotten some interesting responses from them, but never brought a buck in.
You gotta figure something should work!