Used to be whenever I saw a fox or a bobcat cross the road in my highbeams I'd stop and practice my lipsqueaking technique. Gray fox can be called right back to the truck most of the time. Bobcats probably half the time.
Early on, someone showed me how to sound like a rat being constricted by a gopher snake using the crook of my wetted index finger (come to think of it they used the crook of their own wetted finger, not mine!) This has called many a critter to the camera for me ever since. Several bobcats have nearly crawled into my lap. Almost always can coax them closer with the squeak. When I've got something coming at a trot, I'll often stop the ecaller or blowing the tube and just squeak them in from there. This applies mostly to cats and fox, though.
Wetted-finger-crook bit is fairly loud, but it's nowhere near as loud as a reed and tube call. Can't say I've kept a count of how many coyotes, but I've called some over the years... a pack of a half dozen in the snow on the edge of Yosemite one winter evening. But definitely fewer than other species. Yotes just don't crawl into your lap on the creep, though they might well barrel over top of you... But more often they'll bust me further out, especially using a mouth call of any kind, including lipsqueaks. Also since they tend to come much, much further on the run than anything else, and inhabit open grassland here, I initially think of using more volume, and reach out to them with a Circe Jackrabbit tube or an ecaller instead. That said, I've had yotes respond to a lipsqueak from several hundred yards away, so it may be that the ultrahigh pitch of a lipsqueak just carries better than most other calls. And after you've been busted on the tube call and a yote has turned tail and is running away, sometimes they can be made to stop and look back for a moment with the lipsqueak. (Sometimes.)
More than once I've traded yaps and howls and yodels for upwards of a half an hour--haven't ever once budged a yote an inch closer doing this that I recall, but do remember it always hurt my voicebox for the next several days. Loads of fun though.
LionHo