If your long term goal is to hike off leash with your dog, we recommend using a whistle to call your dog. The whistle carries further than your voice and it always sounds the same. So conditioning your dog during your intermediate training to the whistle recall makes a lot of sense.
It is important to remember that just because your dog responds to a whistle in a fenced enclosure does not mean the dog will respond off leash under a strong distraction. We must take our dog through the layering in corrections part of training to build fluency.
This video is taken directly out of our online course and DVD, Intermediate Dog Obedience