My lovely wife bought me a Johnny Stewart PM-4 wireless caller for our anniversary
earlier this week.I went out for a hunt right after sunrise yestersay morning in the national forest (wanted to get out earlier but have been sick and was hacking too much)
First setup I was about a mile from the truck and on an overgrown clear cut with fresh rabitt and fox sign. 10 minutes into the setup I call in my first dog. A big ol' yello lab
and it's female owner right behind it. 18* outside, a mile from the road and she goes for a walk with fido? 
Second setup was a bust but did find plenty of fox sign in the light snow from the night before. I need to get in there before sunup or right at sunset and try again. I did track one fox a ways who was bleeding from his paw and possibly elsewhere. No idea what happened to him but I followed his track for a long ways and never found him.
Can't wait to get back out and try this caller some more. So far I am very happy with it.