Some of the most exciting hunts you can make involve calling. Whether it's a bugling bull elk, a gobbling tom turkey, ducks, geese, varmints or even white-tailed deer -- to have the animal you're after respond to a call is the pinacle of acheivement for many hunters ... and hunting guides.
No matter what you're hunting, if you enjoy calling and are good and experienced at it, by all means you should call. However, if you're new to hunting, or at least the game you are hunting, then consider using the hunt as a learning opportunity. Take your call(s) along, but ask the guide to help you learn.
As with all questions like, this you should discuss the calling with the outfitter ahead of the hunt. If you'll be hunting as part of a group that extends beyond you and your buddies, like often happens in goose hunting for example, there will probably be a standing policy that only the guides call. That way you can't be blamed for "messing up" and preventing birds from coming in range.
If the outfitter and guide are agreeable, tag team calling can be highly effective. For example, in turkey calling, perhaps you're really good with a slate call, making all those subtle noises a hen makes as she's traveling through the woods. Your guide may be a great mouth caller or even produce outstanding gobble calls. By each focusing on your strengths and working as a team, you can produce calling that's irresistable to a big old tom. Same goes for elk, deer, varmint and waterfowl calling. Tag teaming and utilizing your strengths is the way to go.
You can also agree with your guide for you to call up to a certain point, then he or she takes over. A great example of that is elk hunting. You can do all the calling until that bull hangs up. Then the guide backs off leaving you in position. He starts cow calling farther away from the bull in the attempt to make the bull think the cow of his desires is leaving. This can put the bull right in your lap and in perfect position for a shot.
The most important recommendation is to work this out ahead of the hunt with the outfitter and discuss it in camp with the guide before you head into the woods. A clear understanding of who is going to do what will make the hunt more enjoyable and boost your odds for success.