Because a werewolf's senses are immensely attuned to his own kind, particularly with those who are of the same Pack, they're able to communicate with their fellow members very effectively and over immense distances.
They're able to use their voices to snap fellow Pack members out of non-responsive states such as a purely animalistic bloodlust or a health-related unconsciousness. In Unleashed, Scott McCall growled Isaac Lahey's name at the latter. Isaac then snapped out of a state of bloodlust. In Required Reading, Liam Dunbar, using the same technique, enthralled Scott out of a psychosomatic-enabled asthma attack.
The most particularly common werewolf voice is the roar of an Alpha, with is used to restrain, or force the shift upon, other lesser canine shifters.