calling coyotes boils down to this.
A coyote has to hear your call, and he has to make the decision to respond. If there isn't a coyote in the area, it's impossible to call him in.
There is no secret cadence, sound, tone, call, whatever......I've called dogs in with tons of sounds, hell, I've even heard of guys using a tape recording of a baby crying to call in coyotes. I could tell story after story of calling and sets, but, we don't have time.
As said above, there is a lot that goes into it. Be able to use all sounds, prey, big and small, coyote vocals, mating calls, distress etc......
Calling in and killing coyotes to me is the most exciting hunting that I do. Period. Every coyote is a trophy, big or small. It's not like you're deer hunting and waiting for that "one monster buck" and passing up a ton of decent deer. Every last mangy, deer killing, fur turbo is a trophy.