So far, Sanya doesn't seem to really care but...I have it marked down on my cheat sheet for certain frequently used routes. If you can't figure it out and don't have the frequency, ask the present ATC what the next frequency is. Seems to work. Just in case the government has an issue with the government of the country your airline is from and wanting to make an issue as they did with Emirates...just CYA and call when required.