I have an old cell phone to use as a close range predator call. Mostly fox, but have seen a coyote on the cameras since february.  First time in 10 years.  I'm thinking of putting an old cell phone in a rabbit fur hat in the open, setting up on it from a blind or tree stand dawn/dusk (at least until I get set up completely for NV hunting).  Is there an app that has a time delay ("lead") before the calling starts, so that I can place the decoy/call, then get set up and wait until the world forgets I'm there before the rabbit squeals start?  Any place to find a media file such as this?  It's not a full time thing.  I don't want the pelts either, just keeping the population down since we have chickens/goats.  I've seen predator calls with remote for sale. Just don't want to invest too much into this, although it seems predator hunting could be exciting.

Maybe a bluetooth speaker and keep your cell phone in the blind with you. That would enable you to switch up the calls or trigger it at will.
https://www.amazon.com/Extreme-Dimension-Wildlife-Calls-Electronic/dp/B01BE8IKNU

Varmint Al has several sounds and a time delay no sound option. Look under the coyote hunting section for free sounds. An amplified speaker would be much better than just a phone speaker.

Hand/mouth calls can be found cheap.