Use your mouth. It sounds better than any call. Listen to owls in the woods and practice what they do. It may take a while but you can do it. If you use your mouth try sticking your tounge out under your lower lip. Make it look like you have a dip in your mouth. Do it to one side. This will help make your pitch better. I agree it's best to use the owl call in the morning, especially when it's just starting to turn light. It works also when you try to roost a bird for the next morning, sometimes.