All fences wireless or not, you may experience a "run through". Dogs, especially mine, love to chase small furry things. They'll run right through them and not even know it, and then when they come walking back they get zapped and cant come home.
My advice gentlemen, professional dog training. Its like $100 at 'petsma#t' and well worth it. Those units cost up to $300+. And your dog learns more than a boundary. And I think they come with some kind of guarantee. I have a redbone coonhound, and she can now come out in the front yard with us and just watches cats and squirrels. She is a different dog now. Its amazing. And she is not just a house dog, she'll track wounded deer for me too. (they don't teach that in school)