This is my behavioral approach to train my dog… Every time I give my dog a treat I say the word “treat” and whistle. By doing this, I am teaching the dog to come when he hears “treat” or my whistle. So lets say the dog gets out of the yard. I call for him but he doesn’t respond. I try whistling and my dog comes running home.
I also do something similar when I put his bowl of food down; I say “hungry boy.” If he doesn’t respond to “treat” or my whistle, he may respond to, “hungry boy.”
If I can’t whistle then I would purchase a whistle from a sporting goods store, and if the dog is overfed this may not work.