For communication wolves use howl, with a lot of shades, sniffing and barking, growling, clicking teeth, whining, yelping.
Wolf howl always has a specific meaning. It can mean the threat, anguish, despair, sadness, signal captured the prey, to warn of danger.
A wolf's howl can be a single or group. By giving a voice, lone wolf informs about the location, warn of danger, or that this territory is occupied. Group howl of a wolf pack suggests that this area is busy and intruders are not welcome.