Henry is right. It applies the same rules in Cebuano. You don't have to use "si" if you are addressing someone directly. :)

I don't speak Cebuano, but in Tagalog, when you are addressing someone directly, you don't use "si". Kumusta si Sam? = How is Sam? Kumusta kay Sam. = Say hello to Sam for me. Kumusta, Sam? = Though this may also be understood as "How are you, Sam?", it may be said to simply mean, "Hi/Hello, Sam! Kumusta ka, Sam? = How are you, Sam?